[lld] [llvm] MIPS: Use pcrel|sdata4 for eh_frame (PR #91291)

[Fangrui Song via llvm-commits]

MaskRay wrote:

Using DW_EH_PE_sdata4 is a step forward but I was confused by the description as well.

> Maybe we should switch back to sdata8 once GNU LD supports it well.

Looks good. I suspect that the number of MIPS users is small enough that we can require compilers to have a higher version.

https://github.com/llvm/llvm-project/pull/91291