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)

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    605,
 /**/
     604,
 /**/