[llvm-dwp] Deduplicate strings in the debug_str.dwo section

Also, ensure that references to those strings in debug_str_offsets.dwo
correctly refer to the deduplicated strings.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254441 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed