patch 9.0.0965: using one window for executing autocommands is insufficient

Problem:    Using one window for executing autocommands is insufficient.
Solution:   Use up to five windows for executing autocommands.

src/main.c

@@ -123,6 +123,8 @@ main
 #endif
     params.window_count = -1;
 
+    autocmd_init();
+
 #ifdef FEAT_RUBY
     {
 	int ruby_stack_start;