Some network selftests defined variable-sized types variable at the middle
of struct causing -Wgnu-variable-sized-type-not-at-end warning.

warning:
timestamping.c:285:18: warning: field 'cm' with variable sized type
'struct cmsghdr' not at the end of a struct or class is a GNU
extension [-Wgnu-variable-sized-type-not-at-end]
  285 |                 struct cmsghdr cm;
      |                                ^

ipsec.c:835:5: warning: field 'u' with variable sized type 'union
(unnamed union at ipsec.c:831:3)' not at the end of a struct or class
is a GNU extension [-Wgnu-variable-sized-type-not-at-end]
  835 |                 } u;
      |                   ^

This patch move these field at the end of struct to fix these warnings.

Signed-off-by: Ankit Khushwaha <redacted>
---
Changelog:
v2: https://lore.kernel.org/linux-kselftest/20251027050856.30270-1-ankitkhushwaha.linux@gmail.com/ (local)
- fixed typos in the commit msg.

---
 tools/testing/selftests/net/ipsec.c        | 2 +-
 tools/testing/selftests/net/timestamping.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/net/ipsec.c b/tools/testing/selftests/net/ipsec.c
index 0ccf484b1d9d..36083c8f884f 100644
--- a/tools/testing/selftests/net/ipsec.c
+++ b/tools/testing/selftests/net/ipsec.c

@@ -828,12 +828,12 @@ static int xfrm_state_pack_algo(struct nlmsghdr *nh, size_t req_sz,
                struct xfrm_desc *desc)
 {
        struct {
+               char buf[XFRM_ALGO_KEY_BUF_SIZE];
                union {
                        struct xfrm_algo        alg;
                        struct xfrm_algo_aead   aead;
                        struct xfrm_algo_auth   auth;
                } u;
-               char buf[XFRM_ALGO_KEY_BUF_SIZE];
        } alg = {};
        size_t alen, elen, clen, aelen;
        unsigned short type;

diff --git a/tools/testing/selftests/net/timestamping.c b/tools/testing/selftests/net/timestamping.c
index 044bc0e9ed81..ad2be2143698 100644
--- a/tools/testing/selftests/net/timestamping.c
+++ b/tools/testing/selftests/net/timestamping.c

@@ -282,8 +282,8 @@ static void recvpacket(int sock, int recvmsg_flags,
        struct iovec entry;
        struct sockaddr_in from_addr;
        struct {
-               struct cmsghdr cm;
                char control[512];
+               struct cmsghdr cm;
        } control;
        int res;