Timer management code often loops over the list of timers, calling
independant callbacks that end up freeing other timers in the list. That
would result in potentail access-after-free errors, as reported in #105160.
The typical identified scenario is wmTimer calling wmJob code, which
calls some of the job's callbacks (`update` or `end` e.g.), which call
`WM_report`, which removes and add another timer.
To address this issue on a general level, the deletion of timers is now
deferred, with the public API `WM_event_remove_timer` only marking the
timer for deletion, and the private new function
`wm_window_delete_removed_timers` effectively removing and deleting all
marked timers.
This implements design task #105369.
Pull Request #105380
Bastien Montagne