Revert "DebugInfo: Emit the definition of enums when the definition preceeds the declaration and initial use."

This is breaking the compiler-rt build. Reverting while I
investigate/fix.

This reverts commit r208065.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@208106 91177308-0d34-0410-b5e6-96231b3b80d8