swift

456897c2 - [ClangImporter] NS_ERROR_ENUMs can be redefined in separate modules (#20527)

[ClangImporter] NS_ERROR_ENUMs can be redefined in separate modules (#20527) It's not something that /ought/ to happen, but when modules aren't quite set up properly (often by accident, thanks to header maps), we can get into basically this situation by having the definition end up in a header that's textually included into two different modules, or into a module and a bridging header. Handle that the same way we handle other redeclarations: have it show up in both modules. rdar://problem/45646620 (cherry picked from commit 647dd402d5781805c9d2727b1e1799bfc71d42d5)