selftests: xsx: Make pthreads local scope

Make the pthread_t variables local scope instead of global. No reason
for them to be global.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/bpf/20210907071928.9750-14-magnus.karlsson@gmail.com

tools/testing/selftests/bpf/xdpxceiver.c

@@ -887,6 +887,7 @@ static void testapp_validate_traffic(struct test_spec *test)
 	struct ifobject *ifobj_tx = test->ifobj_tx;
 	struct ifobject *ifobj_rx = test->ifobj_rx;
 	struct pkt_stream *pkt_stream;
+	pthread_t t0, t1;
 
 	if (pthread_barrier_init(&barr, NULL, 2))
 		exit_with_error(errno);

tools/testing/selftests/bpf/xdpxceiver.h

@@ -138,8 +138,6 @@ struct test_spec {
 	char name[MAX_TEST_NAME_SIZE];
 };
 
-/*threads*/
 pthread_barrier_t barr;
-pthread_t t0, t1;
 
 #endif				/* XDPXCEIVER_H */