[PATCH] [IndVarSimplify] Widen loop compares for unsigned IVs that have a uniform step of one.

[Chad Rosier]

FWIW, my commit that reverted unsigned comparison widening (r217962) was speculative and just so happened to appease the buildbots.  I suspect the real issue was addressed in r218539.

http://reviews.llvm.org/D5526