Bypass broken fade-out path to eliminate double-free recursion

[jEsuSdA]

Summary

Bypasses the broken fade-out path in destroy_win() to eliminate a recursive double-free crash.

Problem

The fade-out path is broken:

1. destroy_win() calls set_fade() with destroy_callback as the callback
2. When the fade completes, dequeue_fade() calls destroy_callback()
3. destroy_callback() calls finish_destroy_win()
4. finish_destroy_win() calls cleanup_fade()
5. cleanup_fade() calls dequeue_fade() again
6. dequeue_fade() calls destroy_callback() again on the same win*
7. finish_destroy_win() runs a second time on the freed/already-destroyed win*, causing a double-free / use-after-free

Solution

Since fading is already known to be broken and not maintained, the safest fix is to bypass the fade-out path entirely. destroy_win() now always calls finish_destroy_win() directly, and the unused destroy_callback is removed.

This eliminates the recursive double-free while keeping the code simpler. Note: fade-in (set_fade on map) is unaffected and continues to work if enabled.

Scope

• Only fastcompmgr.c is touched
• make clean && make produces zero warnings, zero errors

Impact

Eliminates a crash path during window destruction. No functional change for users who do not use fading (the default).