patch 8.1.0864: cannot have a local value for 'scrolloff' and 'sidescrolloff'

Problem:    Cannot have a local value for 'scrolloff' and 'sidescrolloff'.
            (Gary Holloway)
Solution:   Make 'scrolloff' and 'sidescrolloff' global-local. (mostly by
            Aron Widforss, closes #3539)
diff --git a/src/gui.c b/src/gui.c
index 3996895..d993bc6 100644
--- a/src/gui.c
+++ b/src/gui.c
@@ -4405,7 +4405,7 @@
 #endif
 	    )
     {
-	if (p_so != 0)
+	if (get_scrolloff_value() != 0)
 	{
 	    cursor_correct();		/* fix window for 'so' */
 	    update_topline();		/* avoid up/down jump */