Add "fall through" comments where necessary

Make gcc 7.0.1 happy

Acked-by: Frediano Ziglio <fziglio@redhat.com>

server/dcc.c

@@ -881,8 +881,9 @@ int dcc_compress_image(DisplayChannelClient *dcc,
             break;
         }
 #endif
-lz_compress:
+        /* fall through */
     case SPICE_IMAGE_COMPRESSION_LZ:
+lz_compress:
         success = image_encoders_compress_lz(&dcc->priv->encoders, dest, src, o_comp_data);
         if (success && !bitmap_fmt_is_rgb(src->format)) {
             dcc_palette_cache_palette(dcc, dest->u.lz_plt.palette, &(dest->u.lz_plt.flags));

server/inputs-channel.c

@@ -258,8 +258,8 @@ static bool inputs_channel_handle_message(RedChannelClient *rcc, uint16_t type,
             key_down->code == SCROLL_LOCK_SCAN_CODE) {
             activate_modifiers_watch(inputs_channel, reds);
         }
-        /* fallthrough */
     }
+        /* fallthrough */
     case SPICE_MSGC_INPUTS_KEY_UP: {
         SpiceMsgcKeyUp *key_up = message;
         for (i = 0; i < 4; i++) {

server/reds.c

@@ -776,6 +776,7 @@ static RedPipeItem *vdi_port_read_one_msg_from_device(RedCharDevice *self,
             }
             dev->priv->message_receive_len = dev->priv->vdi_chunk_header.size;
             dev->priv->read_state = VDI_PORT_READ_STATE_GET_BUFF;
+            /* fall through */
         case VDI_PORT_READ_STATE_GET_BUFF: {
             if (!(dev->priv->current_read_buf = vdi_port_get_read_buf(reds->agent_dev))) {
                 return NULL;
@@ -787,6 +788,7 @@ static RedPipeItem *vdi_port_read_one_msg_from_device(RedCharDevice *self,
             dev->priv->message_receive_len -= dev->priv->receive_len;
             dev->priv->read_state = VDI_PORT_READ_STATE_READ_DATA;
         }
+            /* fall through */
         case VDI_PORT_READ_STATE_READ_DATA: {
             n = sif->read(reds->vdagent, dev->priv->receive_pos, dev->priv->receive_len);
             if (!n) {