Make NNAPI countNumberOfConsumers return GeneralResult -- runtime

Previously, countNumberOfConsumers would trigger a CHECK if the input
was invalid. This CL makes countNumberOfConsumers gracefully fail on
errors, instead returning the error through the GeneralResult.

Bug: N/A
Test: mma
Change-Id: I904e5712c29d6ff1a119d9d987cfdaa375479004
Merged-In: I904e5712c29d6ff1a119d9d987cfdaa375479004
(cherry picked from commit b7877954f117ab940240d1efc4e7a756611ad45f)
4 files changed