[ThinLTO]Mark referencers of local ifunc not eligible for import (#92431)

If an ifunc has local linkage, do not add it into ref edges and mark its
referencer (a function or global variable) not eligible for import. An
ifunc doesn't have summary and ThinLTO cannot promote it. Importing the
referencer may cause linkage errors.

To reference a similar fix, https://reviews.llvm.org/D158961 marks
callers of local ifunc not eligible for import to fix
https://github.com/llvm/llvm-project/issues/58740