Split the clang and clang-libs packages
This allows the average Arch user to install the Mesa OpenCL drivers, while installing some ~80 MiB for the libraries. Otherwise they would be getting the whole clang (209) + gcc (185) + compiler-rt (37).
While this was inspired by the size-constraints we have on the SteamDeck, the idea stands on it's own right. After all we do the same with llvm and llvm-libs.
Closes: #1
Note: I am marking this as draft, since the current handling (moving the libraries out during packaging stage) is unlikely to fly. The more idiomatic approach seems to be: install to fakeinstall, copy (_install) respective files in the packages.
Nevertheless, I've opened this to see if the idea with fly with maintainers.