Martin Storsjö authored May 29, 2017 and Anton Mitrofanov committed Jun 14, 2017

The existing functions could easily be used by just calling them
twice - this would give the following cycle numbers from checkasm:

             Cortex A7     A8     A9   A53
var2_8x8_c:       7302   5342   5050  4400
var2_8x8_neon:    2645   1612   1932  1715
var2_8x16_c:     14300  10528  10020  8637
var2_8x16_neon:   5127   2695   3217  2651

However, by merging both passes into the same function, we get the
following speedup:
var2_8x8_neon:    2312   1190   1389  1300
var2_8x16_neon:   4862   2130   2293  2422