Simplify net_send_all()

There is no need to declare the variable before the loop.

app/src/util/net.c

@@ -116,9 +116,8 @@ net_send(socket_t socket, const void *buf, size_t len) {
 ssize_t
 net_send_all(socket_t socket, const void *buf, size_t len) {
     size_t copied = 0;
-    ssize_t w = 0;
     while (len > 0) {
-        w = send(socket, buf, len, 0);
+        ssize_t w = send(socket, buf, len, 0);
         if (w == -1) {
             return copied ? (ssize_t) copied : -1;
         }