selftests: forwarding: Exit with error when missing dependencies

We already return an error when some dependencies (e.g., 'jq') are
missing so lets be consistent and do that for all.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/forwarding/lib.sh

@@ -50,7 +50,7 @@ fi
 
 if [[ ! -x "$(command -v $MZ)" ]]; then
 	echo "SKIP: $MZ not installed"
-	exit 0
+	exit 1
 fi
 
 if [[ ! -v NUM_NETIFS ]]; then