Previous we were issuing an error when linking a module containing
the new Objective-C metadata structure for class properties with an
"old" one.
Now instead we downgrade the module flag so that the Objective-C
runtime does not expect the new metadata structure.
This is consistent with what ld64 is doing on binary files.
Differential Revision: https://reviews.llvm.org/D24620
llvm-svn: 281685
Mehdi Amini