DebugInfo: simplify some limited/declaration creation APIs

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188214 91177308-0d34-0410-b5e6-96231b3b80d8
DebugInfo: Simplify declaration building code - relying on the limit debug info checking already in CreateType(RecordType)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188222 91177308-0d34-0410-b5e6-96231b3b80d8
ObjectiveC migration. Add couple of routine
, currently unused, for future cf-annotation work.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188224 91177308-0d34-0410-b5e6-96231b3b80d8