[ms-cxxabi] Mangle vector types

Summary:
The only vector types a user can pass from MSVC code to clang code are
the ones from *mmintrin.h, so we only have to match the MSVC mangling
for these types.  MSVC mangles the __m128 family of types as tag types,
which we match.  For other vector types, we emit a unique tag type
mangling that won't match anything produced by MSVC.

Reviewers: rjmccall

CC: chandlerc, timurrrr, cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D576