[PATCH] Don't run diagnostic for sanitizer arguments several times

[Richard Smith]

  Perhaps we should lazily construct and store a SanitizerArgs instance on the Driver, and share it between the various places that want to inspect the sanitizer arguments?

  I don't think there's any good reason that the SanitizerArgs implementation mostly lives in the header. Since it's only included into two .cpp files, I don't think it matters much. Fix if you like :-)

http://llvm-reviews.chandlerc.com/D1300