[llvm] [PowerPC][JITLink] Support R_PPC64_GOT_TLSGD_PCREL34 (PR #68660)

[Kai Luo via llvm-commits]

bzEq wrote:

Added TLS test for pwr10. Since requiring different PLT stubs for the same external symbol is rare(need `__attribute__((target(...)))`), I currently mark it as FIXME.

https://github.com/llvm/llvm-project/pull/68660