[mach-o] fix uninitialized variable

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@194290 91177308-0d34-0410-b5e6-96231b3b80d8
[mach-o] revert gunk added to test cases to debug build bot failures

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@194292 91177308-0d34-0410-b5e6-96231b3b80d8