[XDRESS-ONLY] [libclang/python] Hack libclang to be 3.2-3.4 compatible

This commit is to be used solely in the xdress copy of libclang.
It allows us to use a new, modified version of libclang with an
installed older version of clang.  This commit makes it work for
clang 3.2, 3.3, and 3.4.