patch 8.2.0295: highlighting for :s wrong when using different separator

Problem:    Highlighting for :s wrong when using different separator.
Solution:   Use separat argument for search direction and separator. (Rob
            Pilling, closes #5665)
diff --git a/src/spell.c b/src/spell.c
index 87c8f8a..5fdcc3a 100644
--- a/src/spell.c
+++ b/src/spell.c
@@ -2861,7 +2861,7 @@
     curwin->w_cursor.lnum = 0;
     while (!got_int)
     {
-	if (do_search(NULL, '/', frompat, 1L, SEARCH_KEEP, NULL) == 0
+	if (do_search(NULL, '/', '/', frompat, 1L, SEARCH_KEEP, NULL) == 0
 						   || u_save_cursor() == FAIL)
 	    break;