For now, we can use media-libs/mesa present within the
Asahi Linux overlay. It has been added once again with
custom patches.

This manually applies https://gitlab.gnome.org/GNOME/evolution/-/commit/9e3019a0961e91e5fbffe190b973a47c7fafd361
which updates Evolution to utilize API changes for gnome-desktop 43.0.

This should be safe to revert and resolv whenever GNOME 43.0 becomes more
stable on Gentoo.

Eventually, this will not be necessary.
However, upstream Gentoo is currently holding out
until the Asahi drivers make it upstream:
https://bugs.gentoo.org/881669

We should not use pci.0 (the AGP bus) or pci.1 (internal bus),
so we're left with pci.2 (the main bus that things should actually utilize).

However, this is currently hardcoded to only be allowed for pSeries
machines. We can add ourselves in temporarily while this is being
handled upstream.

See also:
 - https://gitlab.com/qemu-project/qemu/-/issues/1146
 - https://gitlab.com/libvirt/libvirt/-/issues/360

Similar to that of net-libx/gtk-vnc, we default to using
the ucontext coroutines backend - requiring context support,
which musl lacks. We enforce gthreads.

Per Gentoo bug #737266 (https://bugs.gentoo.org/737266),
the default Meson build system erroneously assumes the existence
of context-related functions under musl. We default to gthread as
the coroutine provider in order to bypass this detection.

dev-lang/go upstream has dev-lang/go-bootstrap in its tree, which is
very helpful and nulls our purposes. We remove 1.13 in its entirety and
only keep patches to 1.12 as needed.