[lld] ELF,SystemZ: Don't sort relocations for TLS GD/LD optimization; support CREL (PR #149640)

[Ulrich Weigand via llvm-commits]

uweigand wrote:

> CREL does not support random access. To allow the GDCALL/PLT32, we would need to decode them to RELA and sort them first...

Ah, I see.  But it should be possible to "peek" at the next relocation, right?  So we might add something to the main `scanOne` loop to the effect of: if *this* reloc is a `R_390_PLT32DBL` *and* the *next* reloc is a `R_390_TLS_GDCALL` or `R_390_TLS_LDCALL` which we know we'll able to optimize, then simply ignore this (`R_390_PLT32DBL`) reloc?


https://github.com/llvm/llvm-project/pull/149640