Add -print_atoms options to DarwinLdDriver which dumps final state of all atoms in yaml

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@208813 91177308-0d34-0410-b5e6-96231b3b80d8
[mach-o] Add test case for parsing nlist -> Scope

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@208814 91177308-0d34-0410-b5e6-96231b3b80d8
Remove trailing whitespaces.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@208815 91177308-0d34-0410-b5e6-96231b3b80d8