[b43] Timed effects with negative duration

[richardhawk]

Timed effects with negative (like -1) duration should be removed instantly, instead of waiting for the next timed effect tick. This problem is noticeable in game when playing a character with Timeless: even if you reduce the duration of a negative effect such as a stun to -1 or less, you still have to take a turn stunned before it actually wears off.

[darkgod]

fixed