Xext: selinux: drop swapping request length fields

The request struct's length fields aren't used anymore - we have the
client->req_len field instead, which also is bigreq-compatible.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1639>

Xext/xselinux_ext.c

@@ -625,8 +625,6 @@ SProcSELinuxDispatch(ClientPtr client)
 {
     REQUEST(xReq);
 
-    swaps(&stuff->length);
-
     switch (stuff->data) {
     case X_SELinuxQueryVersion:
         return SProcSELinuxQueryVersion(client);