patch 8.2.2518: 'listchars' should be window-local

Problem:    'listchars' should be window-local.
Solution:   Make 'listchars' global-local. (Yegappan Lakshmanan, Marco Hinz,
            closes #5206, closes #7850)
diff --git a/src/drawscreen.c b/src/drawscreen.c
index 694b9da..3fe1c0c 100644
--- a/src/drawscreen.c
+++ b/src/drawscreen.c
@@ -696,7 +696,7 @@
 
 	// In list mode virtcol needs to be recomputed
 	virtcol = wp->w_virtcol;
-	if (wp->w_p_list && lcs_tab1 == NUL)
+	if (wp->w_p_list && wp->w_lcs_chars.tab1 == NUL)
 	{
 	    wp->w_p_list = FALSE;
 	    getvvcol(wp, &wp->w_cursor, NULL, &virtcol, NULL);