Ruby 2.6.5 fails to compile on MacOS Big Sur

After update to Big Sur, the ruby 2.6.5 won't compile. `asdf install ruby 2.6.5` returns the following output:
```
Downloading openssl-1.1.1g.tar.gz...
-> https://dqw8nmjcqpjn7.cloudfront.net/ddb04774f1e32f0c49751e21b67216ac87852ceb056b75209af2443400636d46
Installing openssl-1.1.1g...
Installed openssl-1.1.1g to /Users/bartoszmaka/.asdf/installs/ruby/2.6.5

Downloading ruby-2.6.5.tar.bz2...
-> https://cache.ruby-lang.org/pub/ruby/2.6/ruby-2.6.5.tar.bz2
Installing ruby-2.6.5...
ruby-build: using readline from homebrew

BUILD FAILED (macOS 11.0.1 using ruby-build 20201005)

Inspect or clean up the working tree at /var/folders/q2/0bgpj9917svbst6d9ls2bdfh0000gn/T/ruby-build.20201124095057.44614.wwBG4Q
Results logged to /var/folders/q2/0bgpj9917svbst6d9ls2bdfh0000gn/T/ruby-build.20201124095057.44614.log

Last 10 log lines:
transform_mjit_header: SKIPPED to transform __inline_isinff
transform_mjit_header: SKIPPED to transform __inline_isfinitel
transform_mjit_header: SKIPPED to transform __inline_isfinited
transform_mjit_header: SKIPPED to transform __inline_isfinitef
transform_mjit_header: SKIPPED to transform __darwin_fd_clr
transform_mjit_header: SKIPPED to transform __darwin_fd_set
transform_mjit_header: SKIPPED to transform __darwin_fd_isset
transform_mjit_header: SKIPPED to transform __darwin_check_fd_set
transform_mjit_header: SKIPPED to transform __sputc
ln -sf ../../../.ext/include/x86_64-darwin20/rb_mjit_min_header-2.6.5.h include/ruby-2.6.0/x86_64-darwin20/rb_mjit_min_header-2.6.5.h
```

Those are last lines from compilation log:
```
linking miniruby
ld: warning: dylib (/usr/local/lib/libgmp.dylib) was built for newer macOS version (11.0) than being linked (10.15.6)
rb_mjit_header.h updated
generating encdb.h
building .ext/include/x86_64-darwin20/rb_mjit_min_header-2.6.5.h
./miniruby -I./lib -I. -I.ext/common ./tool/transform_mjit_header.rb "clang " rb_mjit_header.h .ext/include/x86_64-darwin20/rb_mjit_min_header-2.6.5.h
encdb.h updated
./tool/ifchange "--timestamp=.rbconfig.time" rbconfig.rb rbconfig.tmp
rbconfig.rb updated
generating enc.mk
creating verconf.h
verconf.h updated
compiling loadpath.c
making srcs under enc
linking static-library libruby.2.6-static.a
make[1]: Nothing to be done for `srcs'.
generating transdb.h
linking shared-library libruby.2.6.dylib
ld: warning: dylib (/usr/local/lib/libgmp.dylib) was built for newer macOS version (11.0) than being linked (10.15.6)
Undefined symbols for architecture x86_64:
"__mh_execute_header", referenced from:
_rb_dump_backtrace_with_lines in addr2line.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [libruby.2.6.dylib] Error 1
make: *** Waiting for unfinished jobs....
transdb.h updated
```
The same issue occurs with ruby 2.7.2, and ruby 2.6.5 installed via `rvm`