Linfeng Zhang authored Jun 03, 2016 and James Zern committed Jun 08, 2016

Cherry-pick d0ffae82 remove mmx variance functions

there are sse2 equivalents which is a reasonable modern baseline
Removed mmx variance functions:
vpx_get_mb_ss_mmx()
vpx_get8x8var_mmx()
vpx_get4x4var_mmx()
vpx_variance4x4_mmx()
vpx_variance8x8_mmx()
vpx_mse16x16_mmx()
vpx_variance16x16_mmx()
vpx_variance16x8_mmx()
vpx_variance8x16_mmx()

Change-Id: Ife4e67fe85e0012ca560a98831f69195c852a645