[lld] [lld] Properly diagnose R_AARCH64_PREL32 overflow (PR #205963)

[Peter Smith via llvm-commits]

smithp35 wrote:

Raised https://github.com/ARM-software/abi-aa/pull/401 to make R_<CLS>_PREL32 and R_<CLS>_PREL16 signed. Have raised another ABI issue to discuss whether ABS32 and ABS16 should be unsigned, and whether there should be extra signed/unsigned relocations defined https://github.com/ARM-software/abi-aa/issues/402.

As an aside, we're also thinking of some alignment scaled variants of R_<CLS>_PREL32 that could be used by larger code models than small. 

https://github.com/llvm/llvm-project/pull/205963