[mach-o] parse literal sections into atoms

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@209379 91177308-0d34-0410-b5e6-96231b3b80d8
[mach-o] Use lit.local.cfg to enable mach-o test cases to be run

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@209383 91177308-0d34-0410-b5e6-96231b3b80d8