Fix <rdar://problem/6329769> [sema] crash on duplication definition of interface with protocols.

As soon as we detect duplicate interfaces, discontinue further semantic checks (returning the original interface).

This is now consistent with how we handle protocols (and less error prone in general).



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@59541 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed