[libclang] Indexing API: provide both the semantic and the lexical container.

They are generally the same except in C++ cases like out-of-line member functions.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@146069 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed