samples/bpf: run cleanup routines when receiving SIGTERM

Shahid Habib noticed that when xdp1 was killed from a different console the xdp
program was not cleaned-up properly in the kernel and it continued to forward
traffic.

Most of the applications in samples/bpf cleanup properly, but only when getting
SIGINT.  Since kill defaults to using SIGTERM, add support to cleanup when the
application receives either SIGINT or SIGTERM.

Signed-off-by: Andy Gospodarek <[email protected]>
Reported-by: Shahid Habib <[email protected]>
Acked-by: Alexei Starovoitov <[email protected]>
Acked-by: Daniel Borkmann <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
diff --git a/samples/bpf/sampleip_user.c b/samples/bpf/sampleip_user.c
index be59d7d..4ed690b 100644
--- a/samples/bpf/sampleip_user.c
+++ b/samples/bpf/sampleip_user.c
@@ -180,6 +180,7 @@ int main(int argc, char **argv)
 		return 1;
 	}
 	signal(SIGINT, int_exit);
+	signal(SIGTERM, int_exit);
 
 	/* do sampling */
 	printf("Sampling at %d Hertz for %d seconds. Ctrl-C also ends.\n",