Use the CGCXXABI member on CodeGenTypes.

CodeGenTypes already has a reference to a CGCXXABI. Use this directly
rather than going through CodeGenModule to get to the same information.

This is consistent with other references to CGCXXABI in CodeGenTypes
functions defined in CGCall.cpp.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@191854 91177308-0d34-0410-b5e6-96231b3b80d8