Revert "DebugInfo: Don't put fission type units in comdat sections."

This reverts commit r208930, r208933, and r208975.

It seems not all fission consumers are ready to handle this behavior.
Reverting until tools are brought up to spec.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209338 91177308-0d34-0410-b5e6-96231b3b80d8