MDEV-34825 FreeBSD fails to build under clang natively

Upstream the patch from: https://github.com/freebsd/freebsd-ports/blob/15d22e1c70da81aaa5751ad0d82f92e9451c4d81/databases/mariadb106-server/files/patch-mysys_crc32_crc32c.cc

mysys/crc32/crc32c.cc

@@ -455,7 +455,7 @@ static int arch_ppc_probe(void) {
 
   return arch_ppc_crc32;
 }
-# elif defined __FreeBSD_version && __FreeBSD_version >= 1200000
+# elif defined __FreeBSD__
 #  include <machine/cpu.h>
 #  include <sys/auxv.h>
 #  include <sys/elf_common.h>