Add needed cpu feature tests for powerpc architecture.
Overview:
zfs_altivec_available() - needed by RAID-Z
zfs_vsx_available() - needed by BLAKE3
zfs_isa207_available() - needed by SHA2
Part 1 - Userspace
- use getauxval() for Linux and elf_aux_info() for FreeBSD
- direct including <sys/auxv.h> fails with double definitions
- so we self define the needed functions and definitions
Part 2 - Kernel space FreeBSD
- use exported cpu_features of <powerpc/cpu.h>
Part 3 - Kernel space Linux
- use cpu_has_feature() function of <asm/cpufeature.h>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Tino Reichardt <milky-zfs@mcmilk.de>
Closes#13725
Tino Reichardt