[libclang] Introduce clang_Type_getClassType which returns the class type of a member pointer type.

Patch by Che-Liang Chiou!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191906 91177308-0d34-0410-b5e6-96231b3b80d8
[libclang] python: expose a few functions, patch by Loïc Jaquemet!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191907 91177308-0d34-0410-b5e6-96231b3b80d8