Merge "Highbd fht4x4 SSE4.1 optimization for DCT_DCT mode - Setup function vp10_highbd_fht4x4_sse4_1 for highbd SSE4.1   intrinsics optimization. - Wrote SSE4.1 functions: load_buffer_4x4(), write_buffer_4x4(),   and fdct4x4_sse4_1(). - Used logic right shift to avoid coeff memory write/read. - Turned on vp10_highbd_fht4x4_sse4_1 for DCT_DCT mode only. - Improved overall encoding performance >2.3% for 50 frames   sequence, park_joy_1080p_12.y4m, in which, --input-bit-depth=12,   --bit-depth=12, 50 frames. - Unit test passed." into nextgenv2