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/quickfix.c b/src/quickfix.c
index f1df111..7ae489b 100644
--- a/src/quickfix.c
+++ b/src/quickfix.c
@@ -3197,7 +3197,7 @@
 	// Move the cursor to the first line in the buffer
 	save_cursor = curwin->w_cursor;
 	curwin->w_cursor.lnum = 0;
-	if (!do_search(NULL, '/', qf_pattern, (long)1, SEARCH_KEEP, NULL))
+	if (!do_search(NULL, '/', '/', qf_pattern, (long)1, SEARCH_KEEP, NULL))
 	    curwin->w_cursor = save_cursor;
     }
 }