patch 8.2.1059: crash when using :tabonly in an autocommand

Problem:    Crash when using :tabonly in an autocommand. (Yegappan Lakshmanan)
Solution:   Do not allow the autocommand window to be closed.
diff --git a/src/globals.h b/src/globals.h
index c7f9794..03a6937 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -1765,6 +1765,7 @@
 #endif
 EXTERN char e_dirnotf[]	INIT(= N_("E919: Directory not found in '%s': \"%s\""));
 EXTERN char e_au_recursive[]	INIT(= N_("E952: Autocommand caused recursive behavior"));
+EXTERN char e_autocmd_close[]	INIT(= N_("E813: Cannot close autocmd or popup window"));
 #ifdef FEAT_MENU
 EXTERN char e_menuothermode[]	INIT(= N_("E328: Menu only exists in another mode"));
 #endif