udp: adjust receive buffer for windows 7 and earlier

Try to detect runtime what windows version it is running to see if
receive buffers should be increased or leave to OS handling.
Fixes #14200

(cherry picked from commit ca1e15692ce9acc2d421c302434efd10eec64d27)
Signed-off-by: Ilkka Ollakka <ileoo@videolan.org>

src/network/udp.c

@@ -97,6 +97,23 @@ static int net_SetupDgramSocket (vlc_object_t *p_obj, int fd,
 #endif
 
 #if defined (_WIN32)
+
+    /* Check windows version so we know if we need to increase receive buffers
+     * for Windows 7 and earlier
+
+     * SetSocketMediaStreamingMode is present in win 8 and later, so we set
+     * receive buffer if that isn't present
+     */
+    HINSTANCE h_Network = LoadLibraryW(L"Windows.Networking.dll");
+    if( (h_Network == NULL) ||
+        (GetProcAddress( h_Network, "SetSocketMediaStreamingMode" ) == NULL ) )
+    {
+        setsockopt (fd, SOL_SOCKET, SO_RCVBUF,
+                         (void *)&(int){ 0x80000 }, sizeof (int));
+    }
+    if( h_Network )
+        FreeLibrary( h_Network );
+
     if (net_SockAddrIsMulticast (ptr->ai_addr, ptr->ai_addrlen)
      && (sizeof (struct sockaddr_storage) >= ptr->ai_addrlen))
     {