Apparently this is important, otherwise _except_handler3 assumes that
the registration node is corrupted and ignores it.
Also fix a bug in WinEHPrepare where we would insert code after a
terminator instruction.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241877 91177308-0d34-0410-b5e6-96231b3b80d8