[asan] Fix OSX tests.
Support for JavaScript === and !== operators.

Reviewers: klimek, djasper

Reviewed By: klimek

CC: cfe-commits, klimek

Differential Revision: http://llvm-reviews.chandlerc.com/D2231
[mips][msa] Pseudo instructions require HasMSA too. Inherit from MSAPseudo instead of MipsPseudo

There's no test case for this commit. This is because it is doubtful that the
incorrect behaviour can actually trigger. When MSA is not enabled, the type
legalizer should have eliminated all occurrences of patterns the affected
pseudo-instruction could possibly match before instruction selection occurs.
Simplify fix proposed in r195240.
Fix MSVC build

The demangler added in r193708 from cxa_demangle.cpp uses language features which are not supported by the latest visual studio. In order to preserve the msvc build, this patch restores the previous (non)functionality in windows under msvc by disabling the demangler.