[lld] [clang] [flang] [llvm] [AMDGPU] Introduce GFX9/10.1/10.3/11 Generic Targets (PR #76955)

[Pierre van Houtryve via cfe-commits]

Pierre-vh wrote:

Note: testing is a bit light for now, I'd like to add more tests, but I'm not sure what kind of tests are worth adding.
I could just add a generic target run line wherever gfx9/10/11 run lines are present, but that seems a bit overkill? I'd need to change half the tests we have or more.

https://github.com/llvm/llvm-project/pull/76955