if two functions had the same demangled names (constructors where
we have the in charge and not in charge version) we could end up
mixing the two up when making the function in the DWARF. This was
because we need to lookup the symbol by name and we need to use the
mangled name if there is one. This ensures we get the correct address
and that we resolve the linked addresses correctly for DWARf with debug
map.

llvm-svn: 121116