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

This invariant is violated (& the assertions fire) on some Objective C++
in the test-suite. Reverting while I investigate.

This reverts commit r219215.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219523 91177308-0d34-0410-b5e6-96231b3b80d8