[PATCH x86_64] Update memcpy, mempcpy and memmove selection order for Excavator CPU BZ #19583

[Pawar, Amit]

>One question.  If  you don't want __memcpy_avx_unaligned, why do you set AVX_Fast_Unaligned_Load?
Any idea whether currently any other string and memory functions are under implementation based on this? If not then let me just verify it. 

Also this feature is enabled in generic code. To disable it, need to change after this.

--Amit Pawar