[llvm] [AMDGPU] Use absolute relocations when compiling for AMDPAL and Mesa3D (PR #67791)

[Thomas Symalla via llvm-commits]

tsymalla wrote:

The latest changes try to generally generate new registers iff the target does have a register class being set (in the 32-bit and 64-bit case). I wonder how conservative we need to be in terms of reg-class compatibility checks (the PCRel-Case does not do any checks like that).

https://github.com/llvm/llvm-project/pull/67791