[LLD][COFF] When using PCH.OBJ, ensure func_id records indices are remapped under /DEBUG:GHASH

Before this patch, when using LLD with /DEBUG:GHASH and MSVC precomp.OBJ files, we had a bunch of:

lld-link: warning: S_[GL]PROC32ID record in blabla.obj refers to PDB item index 0x206ED1 which is not a LF[M]FUNC_ID record

This was caused by LF_FUNC_ID and LF_MFUNC_ID which didn't have correct mapping to the corresponding TPI records. The root issue was that the indexMapStorage was improperly re-assembled in UsePrecompSource::remapTpiWithGHashes.

After this patch, /DEBUG and /DEBUG:GHASH produce exactly the same debug infos in the PDB.

Differential Revision: https://reviews.llvm.org/D93732