Add ifunc support to ModuleSymbolTable.

Do that by creating a global_values, which is similar to
global_objects, but also iterates over aliases and ifuncs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@299018 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed