Driver: Implement basic --help text.
 - PR3875.
 - <rdar://problem/6615249> [driver] ccc should support some form of
   --help


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@68148 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed