Summary:
Otherwise the definition (first found) for ObjCInterfaceDecl's might
precede the module one, which will eventually lead to crash, since
diagnoseMissingImport needs one coming from a module.
This behavior changed after Richard's r342018, which started to look
into the definition of ObjCInterfaceDecls.
rdar://problem/49237144
Reviewers: rsmith, arphaman
Subscribers: jkorous, dexonsmith, ributzka, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D66982
llvm-svn: 372039
Bruno Cardoso Lopes