Merge "If a general reduction kernel lacks a combiner function, synthesize one."
am: 1ca1ee8

* commit '1ca1ee856d334c7e3bdd7dad6184d10384790512':
  If a general reduction kernel lacks a combiner function, synthesize one.

Change-Id: I579c085edd93169f9cb9db8f9554d96d060dfb14