optional DWARF sections, so compiling with -g does not result in
different code being generated for PC-relative loads.
This is reapplying a diet r197922 (__TEXT-only).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199681 91177308-0d34-0410-b5e6-96231b3b80d8