[WinEH] Add some support for code generating catchpad

We can now run 32-bit programs with empty catch bodies.  The next step
is to change PEI so that we get funclet prologues and epilogues.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@246235 91177308-0d34-0410-b5e6-96231b3b80d8
38 files changed