evas cserve client - fix theoretical size less than 0 issue

theoretically size might be zero but it won't be... but make coverity
happy so it doesn't come back to triage

fix CID 1361430

src/bin/evas/evas_cserve2_client.c

@@ -417,6 +417,7 @@ int main(void)
           }
 
         msg = _msg_types[i].parse_func(&size);
+        if (size <= 0) continue;
 
         if (send(s, &size, sizeof(size), MSG_NOSIGNAL) == -1)
           {