FreeBSD: make adjustments for the standalone environment

In FreeBSD, there are three compile environments that are supported:
user land, the kernel and the bootloader / standalone. Adjust the
headers to compile in the standalone environment. Limit kernel-only
items from view when _STANDALONE is defined.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Warner Losh <imp@FreeBSD.org>
Closes #10998

module/os/freebsd/spl/list.c

@@ -27,10 +27,10 @@
  * Generic doubly-linked list implementation
  */
 
+#include <sys/param.h>
 #include <sys/list.h>
 #include <sys/list_impl.h>
 #include <sys/types.h>
-#include <sys/sysmacros.h>
 #include <sys/debug.h>
 
 #define	list_d2l(a, obj) ((list_node_t *)(((char *)obj) + (a)->list_offset))