Meson: Allow wayland-protocols to be used as a wrap
This series updates uses of
dependency.get_variable, as the latter is deprecated in favor of the former. Then it allows
wayland-protocol to be used as a wrap, by using the
internal argument to
get_variable. This does require a bump to Meson 0.54. It should be helpful for people waiting for distro updates.
This does not check the wrap into the repo, instead on must run
meson wrap install wayland-protocols themselves. There's no reason we couldn't check it in as we do for expat and zlib, but for now I don't want to have that fight.