Check for null ObjCInterfaceDecls returned from getClassInterface() when generating USRs.  While I have no test case for this (could not create one), this shows up in crash reports.  Tentatively fixes <rdar://problem/8452791>.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@114392 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed