Driver: Claim -arch options when pipelining, and claim arguments that

Driver: Claim -arch options when pipelining, and claim arguments that
are forwarded to GCC.
 - The later is unfortunate, as it prevents us from generally warning
   about anything interesting on platforms that use a generic
   toolchain. However, we can't do much better without significantly
   complicating things, and generally we should have proper tool chain
   definitions.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@67293 91177308-0d34-0410-b5e6-96231b3b80d8