Revert "DebugInfo: Ensure that all debug location scope chains from instructions within a function, lead to the function itself."

This reverts commit r212205.

Reverting this again, still seeing crashes when building compiler-rt...
Sorry for the continued noise, not sure why I'm failing to reproduce
this locally.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212226 91177308-0d34-0410-b5e6-96231b3b80d8