Add SHA2 SIMD feature tests for FreeBSD

These are added:
- zfs_neon_available() for arm and aarch64
- zfs_sha256_available() for arm and aarch64
- zfs_sha512_available() for aarch64
- zfs_shani_available() for x86_64

Changes:
- simd_powerpc.h: change license from CDDL to BSD

Tested-by: Rich Ercolani <rincebrain@gmail.com>
Tested-by: Sebastian Gottschall <s.gottschall@dd-wrt.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tino Reichardt <milky-zfs@mcmilk.de>
Closes #13741

include/os/freebsd/Makefile.am

@@ -51,6 +51,8 @@ noinst_HEADERS = \
 	%D%/spl/sys/sid.h \
 	%D%/spl/sys/sig.h \
 	%D%/spl/sys/simd.h \
+	%D%/spl/sys/simd_aarch64.h \
+	%D%/spl/sys/simd_arm.h \
 	%D%/spl/sys/simd_powerpc.h \
 	%D%/spl/sys/simd_x86.h \
 	%D%/spl/sys/spl_condvar.h \