DebugInfo: Improvements/corrections to conservative emission of types in explicit template instantiation declarations

* detect out of line definitions correctly
* detect member function explicit specializations correctly

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@202779 91177308-0d34-0410-b5e6-96231b3b80d8
DebugInfo: Make test (introduced in r202769) resilient to platforms that default to -fstandalone-debug

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@202780 91177308-0d34-0410-b5e6-96231b3b80d8