nl80211: Avoid strict-aliasing warning with gcc 4.7

Signed-hostap: Jouni Malinen <j@w1.fi>

src/drivers/driver_nl80211.c

@@ -5310,7 +5310,7 @@ static int wpa_driver_nl80211_send_mntr(struct wpa_driver_nl80211_data *drv,
 
 	if (noack)
 		txflags |= IEEE80211_RADIOTAP_F_TX_NOACK;
-	*(le16 *) &rtap_hdr[12] = host_to_le16(txflags);
+	WPA_PUT_LE16(&rtap_hdr[12], txflags);
 
 	res = sendmsg(drv->monitor_sock, &msg, 0);
 	if (res < 0) {