* cmds.c (nonundocount): New global variable.

* cmds.c (nonundocount): New global variable.
(keys_of_cmds): Initialize it.
(Fself_insert_command): Use it to combine upto 20 sequential chars
into a single undo entry, just like the Qself_insert_command code in
keyboard.c does.
Call frame_make_pointer_invisible, also like the Qself_insert_command
code in keyboard.c does.
* keyboard.c (command_loop_1): Use the new global nonundocount rather
than its own local replacement for it.