[PATCH] Explicitly report runtime stack realignment in StackMap section

[Andrew Trick]

It looks to me like your change enforces expected behavior. It's great to have a test case. Juergen, do you agree?

Our plan was to add a per function field to the stack map to communicate the dynamic alignment to the runtime. We just haven't done it yet.

Currently, we don't support dynamic alignment, hence no AVX.

http://reviews.llvm.org/D4572