patch 8.0.1445: cannot act on edits in the command line

Problem:    Cannot act on edits in the command line.
Solution:   Add the CmdlineChanged autocommand event. (xtal8, closes #2603,
            closes #2524)
diff --git a/src/ex_getln.c b/src/ex_getln.c
index 421c6b7..837d299 100644
--- a/src/ex_getln.c
+++ b/src/ex_getln.c
@@ -1951,6 +1951,11 @@
 #endif
 
 cmdline_changed:
+#ifdef FEAT_AUTOCMD
+	/* Trigger CmdlineChanged autocommands. */
+	trigger_cmd_autocmd(cmdline_type, EVENT_CMDLINECHANGED);
+#endif
+
 #ifdef FEAT_SEARCH_EXTRA
 	/*
 	 * 'incsearch' highlighting.