[DWARF] Remove unused member and fix(?) the unit-tests on big endian hosts

I can't verified the fix on a big endian host, so I'm not 100% certain it
will work.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@331986 91177308-0d34-0410-b5e6-96231b3b80d8