patch 8.1.0899: no need to check restricted mode for setwinvar()

Problem:    No need to check restricted mode for setwinvar().
Solution:   Remove check_restricted().
diff --git a/src/eval.c b/src/eval.c
index 484f9bc..46d24ef 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -8750,7 +8750,7 @@
     char_u	nbuf[NUMBUFLEN];
     tabpage_T	*tp = NULL;
 
-    if (check_restricted() || check_secure())
+    if (check_secure())
 	return;
 
     if (off == 1)