Revert "[SEH] Remove the old __C_specific_handler code now that WinEHPrepare works"

We still have some "uses remain after removal" issues in -O0 builds.

This reverts commit r235557.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235617 91177308-0d34-0410-b5e6-96231b3b80d8
16 files changed