Update a couple of header inclusion guards

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209980 91177308-0d34-0410-b5e6-96231b3b80d8
ExecutionEngine: avoid NDEBUG in headers

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209981 91177308-0d34-0410-b5e6-96231b3b80d8
Fix typos

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209982 91177308-0d34-0410-b5e6-96231b3b80d8