[PATCH] Driver: implement --dyld-prefix option.

[Rafael Ávila de Espíndola]

  Almost there.

  Would you mind just factoring out a

  StringRef getDynamicLinker() function? That way you can prepend D.DyldPrefix in only one place:

  CmdArgs.push_back(Args.MakeArgString(D.DyldPrefix + getDynamicLinker()));

  LGTM with that change.

http://llvm-reviews.chandlerc.com/D851

BRANCH
  runtime-sysroot

ARCANIST PROJECT
  clang