net-mgmt/aircrack-ng: fix build on powerpc*

FreeBSD doesn't have bits/hwcap.h header and elf_aux_info needs to be used instead of getauxval.

On powerpc platforms there are libraries for Altivec installed and no libraries for AVX and SSE are installed.

PR: 239319
Approved by: lme (maintainer), linimon (mentor)
Differential Revision: https://reviews.freebsd.org/D21040