net: selftests: Add stress_reuseport_listen to .gitignore

Add newly added stress_reuseport_listen object to .gitignore file.

Fixes: ec8cb4f617 ("net: selftests: Stress reuseport listen")
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/.gitignore

@@ -5,6 +5,7 @@ socket
 psock_fanout
 psock_snd
 psock_tpacket
+stress_reuseport_listen
 reuseport_addr_any
 reuseport_bpf
 reuseport_bpf_cpu