[FileCheck] Add -allow-deprecated-dag-overlap to failing clang tests See https://reviews.llvm.org/D47106 for details. Reviewed By: probinson Differential Revision: https://reviews.llvm.org/D47172 git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@336844 91177308-0d34-0410-b5e6-96231b3b80d8