add ff_pixelutils_sad_32x32_sse2, ff_pixelutils_sad_{a,u}_32x32_sse2,
ff_pixelutils_sad_32x32_avx22, ff_pixelutils_sad_{a,u}_32x32_avx2

use perf record/report profiling, get instructions:u for avx2 sad_32x32:

  72.05%  pixelutils  pixelutils     [.] block_sad_32x32_c
  18.50%  pixelutils  pixelutils     [.] block_sad_16x16_c
   4.78%  pixelutils  pixelutils     [.] block_sad_8x8_c
   2.69%  pixelutils  pixelutils     [.] block_sad_4x4_c
   0.89%  pixelutils  pixelutils     [.] block_sad_2x2_c
   0.16%  pixelutils  pixelutils     [.] ff_pixelutils_sad_32x32_avx2
   0.16%  pixelutils  pixelutils     [.] ff_pixelutils_sad_u_32x32_avx2
   0.12%  pixelutils  pixelutils     [.] ff_pixelutils_sad_a_32x32_avx2

sse2 sad_32x32 instructions:u like:

  71.86%  pixelutils  pixelutils     [.] block_sad_32x32_c
  18.42%  pixelutils  pixelutils     [.] block_sad_16x16_c
   4.81%  pixelutils  pixelutils     [.] block_sad_8x8_c
   2.68%  pixelutils  pixelutils     [.] block_sad_4x4_c
   0.88%  pixelutils  pixelutils     [.] block_sad_2x2_c
   0.29%  pixelutils  pixelutils     [.] ff_pixelutils_sad_32x32_sse2
   0.26%  pixelutils  pixelutils     [.] ff_pixelutils_sad_u_32x32_sse2
   0.23%  pixelutils  pixelutils     [.] ff_pixelutils_sad_a_32x32_sse2

Signed-off-by: Jun Zhao <mypopydev@gmail.com>