This commit adds AVX optimized routines for the following
procedures below:
*_compute_peak
*_find_peaks
*_apply_gain_to_buffer
*_mix_buffers_with_gain
*_mix_buffers_no_gain
AVX optimized routine has the prefix of: x86_sse_avx_
Note: mix_buffer_with_gain and mix_buffers_no_gain may prefer
SSE implementaion over AVX if source and destination pointers
are aligned to 16 byte boundaries. Therefore, it will be optimal if
_all_ audio buffers are allocated to 32 byte boundaries to take
full advantage of AVX ISA extension.
03abc1076e