wpa_cli: Support running action script on global control interface

In case wpa_cli is started with an option to execute an action script,
but no interface is specified, wpa_cli might crash in wpa_cli_exec() if
arg1 == NULL. Fix this be setting arg1 = "global".

Signed-off-by: Ilan Peer <ilan.peer@intel.com>

wpa_supplicant/wpa_cli.c

@@ -3659,6 +3659,10 @@ static int wpa_cli_exec(const char *program, const char *arg1,
 	size_t len;
 	int res;
 
+	/* If no interface is specified, set the global */
+	if (!arg1)
+		arg1 = "global";
+
 	len = os_strlen(arg1) + os_strlen(arg2) + 2;
 	arg = os_malloc(len);
 	if (arg == NULL)