fopencookie is a glibc feature, so we can't use it on macOS (and
probably other libc's?). It's only used for the hypervisor interface,
though, so we can just make the hypervisor piece glibc-only while
otherwise fixing the wrap.dylib build.
Fixes: ee83453f69 ("asahi: Add a shared library interface for decode")
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24293>