tree-wide: sort includes

Sort the includes accoding to the new coding style.

src/shared/firewall-util.c

@@ -19,9 +19,9 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
-#include <sys/types.h>
 #include <arpa/inet.h>
 #include <net/if.h>
+#include <sys/types.h>
 #include <linux/netfilter_ipv4/ip_tables.h>
 #include <linux/netfilter/nf_nat.h>
 #include <linux/netfilter/xt_addrtype.h>