[ms-cxxabi] Implement member pointer emission and dereferencing

Summary:
Handles all inheritance models for both data and function member
pointers.

Also implements isZeroInitializable() and refactors some of the null
member pointer code.

MSVC supports converting member pointers through virtual bases, which
clang does not (yet?) support.  Implementing that extension is covered
by http://llvm.org/15713

Reviewers: rjmccall

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D613

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@179305 91177308-0d34-0410-b5e6-96231b3b80d8
Follow Jordan's advice and use {{^}} and {{$}} for this test

This is a better way of ensuring that we match the output of the
rewriter and not the CHECK line.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@179308 91177308-0d34-0410-b5e6-96231b3b80d8
Add a new -mimplicit-float option for symmetry with -mno-implicit-float.

This new option is the default, but it is useful to have a flag to override
-mno-implicit-float by putting -mimplicit-float later on the command line.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@179309 91177308-0d34-0410-b5e6-96231b3b80d8
Exclude test30 of Sema/return.c for Hexagon since setjmp.h include file
is unavailable for Hexagon.


git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@179310 91177308-0d34-0410-b5e6-96231b3b80d8