LLVM/CLANG enable specific targets with varants

[Vincent Habchi]

Folks,

I’ve always wondered what’s the point in letting LLVM/Clang ports build all possible CPU targets. Some of them are really obscure, and I don’t think the commoner needs them (e.g. Hexagon). So I think, given the extra time needed to compile all those superfluous targets, it’d be a nice idea to restrict the default targets to X86 and/or PowerPC and to add a variant to let people who mind build the other targets too. 

What do you think?

Cheers!
Vincent