updated for version 7.4.251

Problem:    Crash when BufAdd autocommand wipes out the buffer.
Solution:   Check for buffer to still be valid. Postpone freeing the buffer
            structure. (Hirohito Higashi)

src/globals.h

@@ -386,6 +386,11 @@ EXTERN int	keep_filetype INIT(= FALSE);	/* value for did_filetype when
 /* When deleting the current buffer, another one must be loaded.  If we know
  * which one is preferred, au_new_curbuf is set to it */
 EXTERN buf_T	*au_new_curbuf INIT(= NULL);
+
+/* When deleting the buffer and autocmd_busy is TRUE, do not free the buffer
+ * but link it in the list starting with au_pending_free_buf, using b_next.
+ * Free the buffer when autocmd_busy is set to FALSE. */
+EXTERN buf_T	*au_pending_free_buf INIT(= NULL);
 #endif
 
 #ifdef FEAT_MOUSE