Including the network_helpers.h header in tests can lead to the following
build error:

./network_helpers.h: In function ‘csum_tcpudp_magic’:
./network_helpers.h:116:14: error: implicit declaration of function \
  ‘htons’ [-Werror=implicit-function-declaration]
  116 |         s += htons(proto + len);

The error is avoided in many cases thanks to some other headers included
earlier and bringing in arpa/inet.h (ie: test_progs.h).

Make sure that test_progs build success does not depend on header ordering
by adding the missing header include in network_helpers.h

Fixes: f6642de0c3e9 ("selftests/bpf: Add csum helpers")
Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>
---
 tools/testing/selftests/bpf/network_helpers.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/bpf/network_helpers.h b/tools/testing/selftests/bpf/network_helpers.h
index c72c16e1aff825439896b38e59962ffafe92dc71..5764155b6d25188ed38e828e1e4a8a08f8a83934 100644
--- a/tools/testing/selftests/bpf/network_helpers.h
+++ b/tools/testing/selftests/bpf/network_helpers.h
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __NETWORK_HELPERS_H
 #define __NETWORK_HELPERS_H
+#include <arpa/inet.h>
 #include <sys/socket.h>
 #include <sys/types.h>
 #include <linux/types.h>

---
base-commit: 67a7c7b656cfc10a7280f71641fb9e88726e8a5d
change-id: 20241008-network_helpers_fix-bbb7d1589930

Best regards,
-- 
Alexis Lothoré, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com