Remove dead code.

Support for exception handling in the legacy JIT was removed in r181354 and
this code was dead since then.

Thanks to Yaron Keren for noticing it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192101 91177308-0d34-0410-b5e6-96231b3b80d8