[PATCH] Don't absolutise path passed to Clang tool

[Manuel Klimek]

  FYI: you forgot to add cfe-commits as CC' on the review (always cc cfe-commits for clang patches, and llvm-commits for llvm changes)

http://llvm-reviews.chandlerc.com/D711

BRANCH
  relative-tool-path

ARCANIST PROJECT
  clang