Speculative build fix for r188206.

The cmake-clang-x86_64 was upset:
error: 'template<class ImplClass, class RetTy> class clang::ConstStmtVisitor' used without template parameters

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188211 91177308-0d34-0410-b5e6-96231b3b80d8
Add hooks to ExternalSemaSource for after-the-fact diagnosis of
incomplete types, courtesy of Luke Zarko.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188212 91177308-0d34-0410-b5e6-96231b3b80d8
clang-cl: Consolidate tests for /Fo and /Fe into cl-outputs.c

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188213 91177308-0d34-0410-b5e6-96231b3b80d8
DebugInfo: simplify some limited/declaration creation APIs

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188214 91177308-0d34-0410-b5e6-96231b3b80d8