[WinEH] Avoid emitting xdata tables twice for cleanups

Since adding invokes of llvm.donothing to cleanups, we come here now,
and trivial EH cleanup usage from clang fails to compile.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234948 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed