[WinEH] Add CoreCLR EH table emission

[WinEH] Add CoreCLR EH table emission

Summary:
Emit the handler and clause locations immediately after the standard
xdata.
Clauses are emitted in the same order and format used to communiate them
to the CLR Execution Engine.
Add a lit test to verify correct table generation on a small but
interesting example function.

Reviewers: majnemer, andrew.w.kaylor, rnk

Subscribers: pgavlin, AndyAyers, llvm-commits

Differential Revision: http://reviews.llvm.org/D13451

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@250219 91177308-0d34-0410-b5e6-96231b3b80d8