slirp: clean up slirp_update_timeout

No need to write out the timeout early, keep it local until we are done.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
diff --git a/slirp.c b/slirp.c
index 8eb5a35..43f1beb 100644
--- a/slirp.c
+++ b/slirp.c
@@ -271,8 +271,8 @@
     if (*timeout <= TIMEOUT_FAST) {
         return;
     }
-    *timeout = MIN(1000, *timeout);
-    t = *timeout;
+
+    t = MIN(1000, *timeout);
 
     /* If we have tcp timeout with slirp, then we will fill @timeout with
      * more precise value.