Add a declaration for `posix_fadvise64` on Linux.

As with the other *64 functions in Linux, `posix_fadvise64` is like
`posix_fadvise` but uses `off64_t` instead of `off_t`.

Bump to 0.2.73

Remove unneeded release step

fix compilation errors

rustfmt

fix style

add f! for const fns

remove unneccessary const functions

rustfmt

Fix style errors

Also simplify some of the phrasing and perform minor grammar tweaks.

This incorporates the changes needed to cross-compile `rustc` for the
aarch64-apple-darwin target.

Revive CI for the switch target

Expose EPOLLEXCLUSIVE on illumos platform

Initially the EPOLLEXCLUSIVE definition was hidden on the illumos
platform as it lacked explicit support.  After further review, it was
concluded that EPOLLEXCLUSIVE can safely be considered a no-op, when not
fully implemented by the OS, making it safe for use on illumos.

openbsd: Fix `WIFSTOPPED` following upstream

https://github.com/openbsd/src/blob/b66614995ab119f75167daaa7755b34001836821/sys/sys/wait.h#L52

Limit macOS `$INODE64` symbol names to x86 and x86_64

The new ARM-based platform doesn't need these as there's no legacy
constraints.

Tested via

**demo.c**

```c

int main() {
  fstat(0, NULL);
  fstatat(0, NULL, NULL, 0);
  lstat(NULL, NULL);
  stat(NULL, NULL);
  readdir(NULL);
  readdir_r(NULL, NULL, NULL);
}
```

**Compilation**

```none
% SDKROOT=/Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.0.sdk MACOSX_DEPLOYMENT_TARGET=11.5 cc -arch arm64 demo.c

% nm a.out
0000000100008030 d __dyld_private
0000000100000000 T __mh_execute_header
                 U _fstat
                 U _fstatat
                 U _lstat
0000000100003e64 T _main
                 U _readdir
                 U _readdir_r
                 U _stat
                 U dyld_stub_binder
```

This has also been experimentally compiled on a Developer Transition Kit.

Bump version ready to import into Android tree.

Fixes #1775

Update emsdk version

Add more WASI libc definitions.