Weapon vissprite not affected by colormaps

[Gez]

Something I noticed while testing invisibility items after the recent changes, however it is not caused by my code, as it's older: the bug is already present in r440, the oldest build available on DRD team. I realize it might be one of those software tricks not supported by GL, but anyway...

Here's how to replicate it simply: start a game of Strife, and summon two shadowarmor items. Pick 'em up both, and use one: your dagger turns translucent. Use the second: in ZDoom, the dagger becomes rendered using the inverted B/W colormap as intended, in GZDoom it remains unchanged.