Merge changes Iebe9842f,I174b67a5,I80ed1a16

* changes:
  vpx_convolve_neon: prefer != 0 to > 0 in tests
  vpx_convolve_avg_neon: prefer != 0 to > 0 in tests
  vpx_convolve_copy_neon: prefer != 0 to > 0 in tests