link ntdll on non-windows-gnu targets (needed for aarch64-pc-windows-gnullvm)

[jeremyd2019]

See also msys2/MINGW-packages#17426. On that, @mati865 suggested that there should be a check to avoid linking ntdll on msvc targets, but I am not sure. winapi has logic in its build.rs to prefix lib names only for i686-pc-windows-gnu or x86_64-pc-windows-gnu, only if WINAPI_NO_BUNDLED_LIBRARIES is not set, but it still links the (unprefixed) libraries on any other target, so I am trying to replicate that here. Let me know if that breaks msvc, and I can try adding an additional check.

Note I don't really know rust, so there may be a more elegant way to write this.