Fix bad tests exposed by parallel reduction support.

findMinAndMax kernel testing must compare cell value not cell index
-- two or more cells might have the same min or max value, and java
and various rs multithreaded executions are not guaranteed to find
the same cell.

Fix bug in combiner functions for kernels findMinAndMaxHalf,
findMinAndMaxHalf2, and findMinAndMaxMat.  (They behaved
incorrectly when operating on an accumulator datum that has been
initialized but never passed to the accumulator function.)

Bug: 27941284
Bug: 27299475
Change-Id: I2ddb298507fb9f8c6eae2122afc1017e25dc12f1
2 files changed