patch 8.0.0605: the quickfix cached buffer may become invalid

Problem:    The buffer that quickfix caches for performance may become
            invalid. (Daniel Hahler)
Solution:   Reset qf_last_bufref in qf_init_ext(). (Daniel Hahler,
            closes #1728, closes #1676)
diff --git a/src/version.c b/src/version.c
index bc80ace..2c5aa06 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    605,
+/**/
     604,
 /**/
     603,