Revert "Reapply debug info changes now that r224385 has been recommitted to clang (in r224941)"

Asserting when building compiler-rt when using a gcc host compiler.
Reverting while I investigate.

This reverts commit r224942.
Revert "DebugInfo: Generalize debug info location handling"

Asserting when building compiler-rt when using a GCC host compiler.
Reverting while I investigate.

This reverts commit r224941.