this removes dri-classic- they are no longer maintained in tree, and there is a separate 'amber' tree for them.
not sure if we should keep them- these are the drivers removed: https://pkgs.alpinelinux.org/contents?file=&path=&name=mesa-dri-classic&branch=edge
except for i915- which has a gallium version, that is supposedly better maintained now anyway.
the tls fixes are also not needed anymore i think- the meson system sets it to -mtls-dialect=gnu2 now, and we don't need to do anything for it.