tree-wide: Sort includes

This was done by running a locally built clang-format with
https://github.com/llvm/llvm-project/pull/137617 and
https://github.com/llvm/llvm-project/pull/137840 applied on all .c
and .h files.

src/nspawn/nspawn-network.c

@@ -1,10 +1,9 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
-/* Make sure the net/if.h header is included before any linux/ one */
-#include <net/if.h>
 #include <linux/if.h>
 #include <linux/nl80211.h>
 #include <linux/veth.h>
+#include <net/if.h>
 #include <sys/file.h>
 #include <sys/mount.h>