compile, depcomp, ylwrap: Fix quoting bug in 'trap' command.

Reported by an AI tool in the name of Michał Majchrowicz.

Based on the idea from Autoconf commit 416b8f50c9bd4e38f9bc48b946505d2a18f6b1fd:
Use a shell function to avoid quoting hassles inside a 'trap' argument.

* lib/compile (cleanup): New function.
(trap): Use it.
* lib/depcomp (cleanup): New function.
(trap): Use it.
* lib/ylwrap (origdirname): New variable.
(cleanup): New function.
(do_exit): Use it.