Extend USE_LIBDAV1D_ENABLE_WEB_RTC macOS usage
<rdar://problem/108249046>
<rdar://107244733>
Pull request: https://github.com/WebKit/WebKit/pull/12907
Committed 263145@main (d68e2987d9f0): <https://commits.webkit.org/263145@main> Reviewed commits have been landed. Closing PR #12907 and removing active labels.