Revert "DebugInfo: Move type units into the debug_types section with appropriate comdat grouping and type unit headers"

This reverts commit r197073.

The test seems to be failing on some buildbots for unknown reasons.
Reverting until I can figure that out. If anyone's got a reproduction
(.s and .o together would be great) - I'd really appreciate it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197079 91177308-0d34-0410-b5e6-96231b3b80d8