Revert "dwarfgen: Add support for generating the debug_str_offsets section"

This reverts commit r337910 as it's generating "ambiguous call to
addAttribute" errors on some bots.

Will resubmit once I get a chance to look into the problem.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@337924 91177308-0d34-0410-b5e6-96231b3b80d8
8 files changed