For dwarf4 use the correct form for referencing debug_loc locations,
and update test cases accordingly.

This doesn't affect the output dumped using llvm-dwarfdump, but
readelf does now dump the debug_loc section.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194898 91177308-0d34-0410-b5e6-96231b3b80d8