[lld] [WIP/RFC][ELF][PowerPC] Don't assume TOC pointer is valid in IPLT entries (PR #207555)

[Jessica Clarke via llvm-commits]

jrtc27 wrote:

We don't treat the .got2 as distinct though, right, we just combine them into one? But yes, the IPLT stub can now be shared and used in any context, and if direct calls can also do interesting things like that then yeah those should be fixed too.

https://github.com/llvm/llvm-project/pull/207555