macOS link fails: cargo run --example locks

On macos, the following two functions don't appear to be available. So the following fails to link or run:
`cargo run --example locks`
You can see the log at the end of this post.

These are the missing funcs on macOS:
```
pthread_rwlock_timedrdlock()
pthread_rwlock_timedwrlock()
```

Interestingly enough, `pthread_mutex_timedlock` is also not available on macOS, but an implementation
has been provided under `if #[cfg(target_os = "macos")] {...`
I wonder if there might be equivalents for pthread_rwlock_timed..lock() where that came from?
It also appears glibc offers a [replacement mentioned HERE](https://www.gnu.org/software/gnulib/manual/html_node/pthread_005frwlock_005ftimedrdlock.html#pthread_005frwlock_005ftimedrdlock)

I am checking to see the authors can suggest where to get a good replacement.
Or if the authors have a good idea about how to fix this?
Thanks, Cameron

```
c@macmini ~/D/r/raw_sync-rs (master) [101]> cargo run --example locks
Compiling raw_sync v0.1.5 (/Users/c/Documents/rs/raw_sync-rs)
error: linking with `cc` failed: exit status: 1
|
= note: "cc" "-m64" "-arch" "x86_64" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.15vmvh72pfa6pnzf.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.1mhvuom1vif64dgp.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.1nl61rjywspj6e2l.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.1o5ku221nvivr1uo.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.20f4z4xoaa4w16j2.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.305h8lr7mfiyvwk4.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.30vnonx6dsngno0.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.34f01fvt4tquz6bz.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.3if3fqhg66h5j3qc.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.3kwmzklrjj7szlxh.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.3pq4vkndw1lzgsvy.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.3pu8s3f0iawz77x2.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.3ql9hfh7lk3uackc.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.40tz8klf0lpn4d4b.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.40uutlfvdgcb5buq.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.410vfbp1bswddlhj.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.42lk811q1nz7fw2h.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.4722xntt5b9kowto.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.49tyyy7rkj9wr8p3.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.4eo467iqjixrgbhi.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.4g6r51ny6t1xj114.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.4gt8305f6hgug1cv.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.4qj2n04vsin1xn6e.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.4wzor2jn3qhctwux.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.50qyhnzsci8nyn3l.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.512o8ca57zr2z10l.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.53jhgxekh2wxbkj.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.56oqlofvcytp228h.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.5ckzsuoquucy7rce.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.gy20ewq43yt2s6a.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.qh8fiu2davjyhki.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.qqyn39fzeof6vo1.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.tqvsw7p2sm0oqxr.rcgu.o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c.4gu86rmkv73c909f.rcgu.o" "-L" "/Users/c/Documents/rs/raw_sync-rs/target/debug/deps" "-L" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib" "/Users/c/Documents/rs/raw_sync-rs/target/debug/deps/libraw_sync-9e3b62dd02c25d59.rlib" "/Users/c/Documents/rs/raw_sync-rs/target/debug/deps/libnix-31bfd5723b91edc4.rlib" "/Users/c/Documents/rs/raw_sync-rs/target/debug/deps/libbitflags-5807c7dc27ea64c8.rlib" "/Users/c/Documents/rs/raw_sync-rs/target/debug/deps/libmemoffset-0059bcb888f9d093.rlib" "/Users/c/Documents/rs/raw_sync-rs/target/debug/deps/libenv_logger-2fb8cd88855d6469.rlib" "/Users/c/Documents/rs/raw_sync-rs/target/debug/deps/libatty-0f41ef3414cde949.rlib" "/Users/c/Documents/rs/raw_sync-rs/target/debug/deps/liblibc-c9fbfbcd791abe60.rlib" "/Users/c/Documents/rs/raw_sync-rs/target/debug/deps/libtermcolor-934608461d59bee3.rlib" "/Users/c/Documents/rs/raw_sync-rs/target/debug/deps/libhumantime-6ae3b1203ddc3145.rlib" "/Users/c/Documents/rs/raw_sync-rs/target/debug/deps/liblog-6692e0a188c29cee.rlib" "/Users/c/Documents/rs/raw_sync-rs/target/debug/deps/libcfg_if-7e74d31581507915.rlib" "/Users/c/Documents/rs/raw_sync-rs/target/debug/deps/libregex-eac4b23977649399.rlib" "/Users/c/Documents/rs/raw_sync-rs/target/debug/deps/libaho_corasick-bd486f8f47a9c700.rlib" "/Users/c/Documents/rs/raw_sync-rs/target/debug/deps/libmemchr-7874de389e22e218.rlib" "/Users/c/Documents/rs/raw_sync-rs/target/debug/deps/libregex_syntax-3d679e5b759db215.rlib" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/libstd-04b20da5d2b4e02d.rlib" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/libpanic_unwind-00f5b50d82ace1e3.rlib" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/libobject-45c041bae4e30a62.rlib" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/libmemchr-1bc22f5f5be77a23.rlib" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/libaddr2line-caa784d0cecbd501.rlib" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/libgimli-0ad46247e89234f6.rlib" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/librustc_demangle-68dabd8f37218f7c.rlib" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/libstd_detect-4c67204728564461.rlib" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/libhashbrown-eca93a0d11ef9a39.rlib" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/librustc_std_workspace_alloc-6ddabe46ef182f8b.rlib" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/libunwind-7dc1037a76f2c18c.rlib" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/libcfg_if-100dc4191a6287d7.rlib" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/liblibc-c596c47fc21af016.rlib" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/liballoc-c7163fef4a8cdd33.rlib" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/librustc_std_workspace_core-3463abc69f183e66.rlib" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/libcore-12a50039d8929e4e.rlib" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib/libcompiler_builtins-a4134bbc9f4f0dab.rlib" "-liconv" "-lSystem" "-lresolv" "-lc" "-lm" "-liconv" "-L" "/Users/c/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/lib" "-o" "/Users/c/Documents/rs/raw_sync-rs/target/debug/examples/locks-adce1879609c609c" "-Wl,-dead_strip" "-nodefaultlibs"
= note: Undefined symbols for architecture x86_64:
"_pthread_rwlock_timedrdlock", referenced from:
_$LT$raw_sync..locks..unix..RwLock$u20$as$u20$raw_sync..locks..LockImpl$GT$::try_rlock::h3295aa08710fdf36 in libraw_sync-9e3b62dd02c25d59.rlib(raw_sync-9e3b62dd02c25d59.2j047qgu8yj7k2nx.rcgu.o)
"_pthread_rwlock_timedwrlock", referenced from:
_$LT$raw_sync..locks..unix..RwLock$u20$as$u20$raw_sync..locks..LockImpl$GT$::try_lock::ha1e205a6fe064f36 in libraw_sync-9e3b62dd02c25d59.rlib(raw_sync-9e3b62dd02c25d59.2j047qgu8yj7k2nx.rcgu.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

error: could not compile `raw_sync` due to previous error
c@macmini ~/D/r/raw_sync-rs (master) [101]>
```