AudioGetCurrentHostTime has been present forever, so the test is not
enforcing a specific version of macOS.  In fact the test was broken
since it was not linking against the coreaudio dependency; just remove it.

Fixes: 87430d5b ("configure, meson: move audio driver detection to Meson", 2021-10-14)
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>