Parallelize DedupBlocksPass
Parallelize DedupBlocksPass

Summary:
Showing 1.2 seconds on my devserver. We'll see what statsbot says

Also a bit of cleanup

Reviewed By: int3

Differential Revision: D5730264

fbshipit-source-id: 1a0ed547a2f068553510d5d432823f632d991efd

facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex