patch 8.0.1669: :vimgrep may add entries to the wrong quickfix list

Problem:    :vimgrep may add entries to the wrong quickfix list.
Solution:   Use the list identifier. (Yegappan Lakshmanan)
diff --git a/src/version.c b/src/version.c
index 33bae20..813bcfa 100644
--- a/src/version.c
+++ b/src/version.c
@@ -763,6 +763,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1669,
+/**/
     1668,
 /**/
     1667,