avx512f: work around AArch64 GCC 7 issue for simde_mm512_load_si512
avx512f: work around AArch64 GCC 7 issue for simde_mm512_load_si512

GCC 7 seems to have trouble with just using *mem_addr; builds on CI
are unreliable.  This just uses memcpy instead, hopefully it fixes
the issue.

nemequ/simde,nemequ/simde,nemequ/simde