Add clang config framework

Compiling for clang is getting trickier to do because the configs are different than gcc in some cases. Mimic the kgcov framework to setup clang to be easier to update their configs.

This framework is designed to blindly merge.py with any configs fed to it. This is unlike the build_configs framework where it uses priority.rhel|fedora rules to merge things.

This leads to strange cases where clang debug configs need different settings than clang non-debug configs. For non-lto clang, due to clang bugs it is easy to disable the debug features and get away with this. But once resolved we will have to reinvestigate. For lto clang, I just hack out the debug and kgcov config files due to clashing Kconfig depend rules.

I don't expect this to be a long term solution. Perhaps when our config rework is fully realized this just melts away. TBD.

Signed-off-by: Don Zickus dzickus@redhat.com