As the ebuild's ewarn notes, --gpu-api=opengl still works with USE=egl
through egl-x11/wayland, this only drops the deprecated/legacy gl-x11.
Debated renaming USE=egl to USE=opengl instead given it's more commonly
used, but given we've been calling it deprecated in metadata.xml and
that mpv options are all egl-* it may come as confusing.
The ewarn is not overly essential given we enable USE=egl by default,
but mpv tend to have a few minimalist users that disable everything
they can. I may add that if do this, may want to consider USE=vulkan
instead if it works well given mpv upstream favours it by default now.
Untested but tentatively add aqua for -Dgl (formerly controlled
through USE=opengl), believe gl-cocoa is always available? Please
report if this causes issues.
Closes: https://bugs.gentoo.org/953107
Signed-off-by: Ionen Wolkens <ionen@gentoo.org>