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

This reverts commit r212085.

This breaks the sanitizer bot... & I thought I'd tried pretty hard not
to do that. Guess I need to try harder.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212089 91177308-0d34-0410-b5e6-96231b3b80d8