patch 7.4.2324

Problem:    Crash when editing a new buffer and BufUnload autocommand wipes
            out the new buffer. (Norio Takagi)
Solution:   Don't allow wiping out this buffer. (partly by Hirohito Higashi)
            Move old style test13 into test_autocmd. Avoid ml_get error when
            editing a file.

src/version.c

@@ -763,6 +763,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2324,
 /**/
     2323,
 /**/