[PATCH] [ELF] Support response file.

[Rui Ueyama]

  I disagree. A response file is not an option, but more like a preprocessor
  directive for the command line. It's like `...` handled not by shell but by
  driver. In the first stage response files are expanded, and in the second
  stage they are processed. We shouldn't mix these stages.

http://llvm-reviews.chandlerc.com/D3210

BRANCH
  responsefile

ARCANIST PROJECT
  lld