ThinLTO: Fix inline assembly references to static functions with CFI

Create an internal alias with the original name for static functions
that are renamed in promoteInternals to avoid breaking inline
assembly references to them.

Relands 700d07f8 with -msvc targets
fixed.

Link: https://github.com/ClangBuiltLinux/linux/issues/1354

Reviewed By: nickdesaulniers, pcc

Differential Revision: https://reviews.llvm.org/D104058