[libclang] When doing clang_findReferencesInFile, make sure we don't crash
if we come up against a null Decl.

No test case unfortunately. rdar://10457799.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@146127 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed