[PATCH] [Core] Add parallel infrastructure to lld.

[Alex Rosenberg]

  We're in the process of putting together a large internal buildbot farm that will include tests almost exactly like the ones Sean has listed.

  I'd love for lab to also be doing some LNTs here.

  I'd also suggest some benchmarking of small resulting executables, as per Sean's point about parallel_sort.

  Alex

http://llvm-reviews.chandlerc.com/D649