[WinEH] Hoist state stores from successors

If we know that all of our successors want to be in the exact same
state, it makes sense to hoist the state transition into their common
predecessor.

Differential Revision: http://reviews.llvm.org/D17391

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@261262 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed