mesa 18

[coypu%sdf.org@localhost]

hi folks,

I have these repos:
https://github.com/coypoop/xsrc
https://github.com/coypoop/src-1


They do:
- Update us to Mesa 18.3.1
- Build LLVM on several archs, even when the chosen compiler is GCC
- Statically link LLVM libraries to gallium
- At some point they built on arm64, m68k, amd64, i386
- Even set lists are OK
- Hack-testing on amd64 with clang too and r300, r600, nouveau, swrast work.

Unfortunately there are a whole pile of issues showing up when testing
them on real platforms, so my current to-do list is:

- Full release on i386 does not run glxgears and has some problems, they
  might be W^X problems? I'm not sure, it was very problematic.
- on rpi3+arm64, running glxgears, I get "Unable to find RGB,
  double-buffered visual".

I also have no non-x86/arm hardware with graphical output, so I am not a
good person to do this task. poewrpc and sparc need separate testing.

Some more minor changes needed:
- Get rid of atexit at dlopen'd libraries
- Centralize -fPIC llvm library handling

I'm not sure what to do next. It is annoying that the to-do list keeps
on growing and netbsd-9 branching comes soon. did those architectures
even have 3D acceleration before?