Support clang_linux-*

[h-vetinari]

This discussion came up in conda-forge/clangdev-feedstock#246 recently:

@h-vetinari: Do I understand you correctly that you're proposing to introduce clang_linux-64?

@xhochy: Yes, but don't expect it to happen anytime soon.

@isuruf: I tried that recently and realized that some of the symlinks are in wrong packages. See my WIP PR conda-forge/ctng-compilers-feedstock#112

That PR has since been merged, so we can use this issue to figure out next steps.

PS. Speaking of symlinks, this issue is also quite closely related to #118.

[h-vetinari]

Ah, it seems that @isuruf already has a PR for this, but on another feedstock: conda-forge/ctng-compiler-activation-feedstock#100 🥳

Regarding the feedstock placement, there's a good explanation as well:

Random question - why is this not in the clang-compiler-activation feedstock?

I think of this feedstock [ctng-compiler-activation] as Linux compilers and the other [clang-compiler-activation] as macOS compilers. This feedstock has much more in common with clang_linux-64 than clang-compiler-activation-feedstock does.

[h-vetinari]

As of conda-forge/ctng-compiler-activation-feedstock#102, it should now be possible to use clang/clangxx also on linux. 🥳

I'm leaving this open for now, because it's still early days and it it's IMO a good place to collect any eventual problems.

[h-vetinari]

Closing as done, c.f. also conda-forge/conda-forge.github.io#2161