MachO: Comment fields in the version_min load command.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204189 91177308-0d34-0410-b5e6-96231b3b80d8
Darwin: Add assembler directives to create version-min load commands.

Allow object files to be tagged with a version-min load command for iOS
or MacOSX.

Teach macho-dump to understand the version-min load commands for
testcases.

rdar://11337778

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204190 91177308-0d34-0410-b5e6-96231b3b80d8
MachO: Emit a version-min load command when possible.

When deployment target version information is available, emit it to the
target streamer for inclusion in the object file.

rdar://11337778

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204191 91177308-0d34-0410-b5e6-96231b3b80d8
Tidy up. Update per naming conventions.

No functional change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204192 91177308-0d34-0410-b5e6-96231b3b80d8