[PATCH] Move LinkerInput to LinkingContext.

[Rui Ueyama]

  For COFF that's different. In COFF, any object file can contain command line options, and the linker should processes the command line options *only when* the object is used for linking. The difference is visible when processing a library file. We cannot tell which object file in a library will be used by the linker until we actually try to link. Interleaving of linking and command line processing is inevitable.

http://llvm-reviews.chandlerc.com/D1569