Remove unneeded use of #undef DEBUG_TYPE. NFC

Where is is needed (at the end of headers that define it), be
consistent about its use.

Also fix a few header guards that I found in the process.

Differential Revision: https://reviews.llvm.org/D34916

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307840 91177308-0d34-0410-b5e6-96231b3b80d8
8 files changed