We got some build failures with DXVK-NVAPI due to this. They even have
CI that uses Proton SDK images but since we create our own cross files
they were not anticipating that we may be forcing a C++ standard
version.
Since everything builds and none of the meson-using subprojects seems to
be setting the version via their provided corss files we should be good
to just drop it.
Parts of the rules, including the magical ones created via
make/rules-*.mk, are executed inside of the container via SHELL
override, and parts are executed on the host side.
This makes reasoning about and debugging the rules much harder than it
should be. It also requirs the users to have certain programs installed
on the host in addition to docker/podman.
With this change `make` will act as a simple pass through to inside of
the container for the most part.
One notable exception is installation which still happens the host side.
