Refactor kill_nonused_tcp()

This makes the code a little more flat and readable. We also change the
logic so that we can kill the necessary number of unused relays immediately
rather than having to collect them and remove them in a separate loop

toxcore/TCP_connection.c

@@ -1438,42 +1438,48 @@ static void do_tcp_conns(const Logger *logger, TCP_Connections *tcp_c, void *use
 
 static void kill_nonused_tcp(TCP_Connections *tcp_c)
 {
-    if (tcp_c->tcp_connections_length == 0) {
+    if (tcp_c->tcp_connections_length <= RECOMMENDED_FRIEND_TCP_CONNECTIONS) {
         return;
     }
 
     uint32_t num_online = 0;
-    uint32_t num_kill = 0;
-    VLA(unsigned int, to_kill, tcp_c->tcp_connections_length);
 
     for (uint32_t i = 0; i < tcp_c->tcp_connections_length; ++i) {
         TCP_con *tcp_con = get_tcp_connection(tcp_c, i);
 
-        if (tcp_con) {
-            if (tcp_con->status == TCP_CONN_CONNECTED) {
-                if (!tcp_con->onion && !tcp_con->lock_count
-                        && mono_time_is_timeout(tcp_c->mono_time, tcp_con->connected_time, TCP_CONNECTION_ANNOUNCE_TIMEOUT)) {
-                    to_kill[num_kill] = i;
-                    ++num_kill;
-                }
+        if (tcp_con == nullptr) {
+            continue;
+        }
 
-                ++num_online;
-            }
+        if (tcp_con->status == TCP_CONN_CONNECTED) {
+            ++num_online;
         }
     }
 
     if (num_online <= RECOMMENDED_FRIEND_TCP_CONNECTIONS) {
         return;
     }
 
-    uint32_t n = num_online - RECOMMENDED_FRIEND_TCP_CONNECTIONS;
+    const uint32_t max_kill_count = num_online - RECOMMENDED_FRIEND_TCP_CONNECTIONS;
+    uint32_t kill_count = 0;
 
-    if (n < num_kill) {
-        num_kill = n;
-    }
+    for (uint32_t i = 0; i < tcp_c->tcp_connections_length && kill_count < max_kill_count; ++i) {
+        TCP_con *tcp_con = get_tcp_connection(tcp_c, i);
 
-    for (uint32_t i = 0; i < num_kill; ++i) {
-        kill_tcp_relay_connection(tcp_c, to_kill[i]);
+        if (tcp_con == nullptr) {
+            continue;
+        }
+
+        if (tcp_con->status == TCP_CONN_CONNECTED) {
+            if (tcp_con->onion || tcp_con->lock_count) {  // connection is in use so we skip it
+                continue;
+            }
+
+            if (mono_time_is_timeout(tcp_c->mono_time, tcp_con->connected_time, TCP_CONNECTION_ANNOUNCE_TIMEOUT)) {
+                kill_tcp_relay_connection(tcp_c, i);
+                ++kill_count;
+            }
+        }
     }
 }