patch 9.0.0998: "gk" may reset skipcol when not needed

Problem:    "gk" may reset skipcol when not needed.
Solution:   Only reset skipcol if the cursor column is less.
diff --git a/src/move.c b/src/move.c
index 14667f3..d976697 100644
--- a/src/move.c
+++ b/src/move.c
@@ -2343,7 +2343,7 @@
     {
 	/*
 	 * If "always" is FALSE, only adjust topline to a lower value, higher
-	 * value may happen with wrapping lines
+	 * value may happen with wrapping lines.
 	 */
 	if (new_topline < curwin->w_topline || always)
 	    curwin->w_topline = new_topline;
@@ -2360,7 +2360,8 @@
 	check_topfill(curwin, FALSE);
 #endif
 	// TODO: if the line doesn't fit may optimize w_skipcol
-	if (curwin->w_topline == curwin->w_cursor.lnum)
+	if (curwin->w_topline == curwin->w_cursor.lnum
+		&& curwin->w_skipcol >= curwin->w_cursor.col)
 	    reset_skipcol();
 	if (curwin->w_topline != old_topline
 		|| curwin->w_skipcol != old_skipcol