When Protocol references are constructed, we need to add the reference
symbol to a COMDAT group on non-MachO object file formats (MachO handles
this by having a coalesced attribute). This adds the missing case.
llvm-svn: 306622
This allows for the coalescing of the protocol declarations. When the protocols
are declared in headers, multiple definitions of the protocol would be emitted.
Marking them as common data indicates that any one can be selected.
llvm-svn: 285073