Option `-Wl,-R` not supported

The `ld` docs say that `-R` is the same as `-rpath` if the provided path is a directory:

```
-R FILE, --just-symbols FILE
Just link symbols (if directory, same as --rpath)
```

But it is a hard error on Emscripten:

```
$ echo 'int main(){ return 0; }' > a.c
$ gcc -Wl,-R/a/b a.c # works
$ clang -Wl,-R/a/b a.c # works
$ emcc -Wl,-R/a/b a.c # fails
wasm-ld: error: unknown argument: -R/a/b
```