D&D Orcs have never been green. Never.
Orcs began their existence under the pen of Tolkien. They were one of the (not that numerous, BTW) things taken from Tolkien by Gygax and Arneson and put into D&D (the others were hobbits, ents, and multiracial adventuring party).
D&D orcs were the militaristic LE hordes, very close to Tolkien's vision of them.
Then came WarHammer, who had a different take on orcs. First, they are even stronger. Secondly, they are definitely stupid -- much more than D&D's ones, and definitely more than Tolkien's ones. Thirdly, they're green. And finally, they're "orks" rather than orcs, because it looks more brutal and stupid with a K.
The WH orks, by the way, are not evoluted pigs, but mushrooms. It's one of the thing you learn in WH40K. And who cares if mushrooms are never green?
Well, the grotesque orks, so undisciplined and idiot that their gruesome violence is overlooked and they are "funny", were so successful they influenced lots of people, probably more than Tolkien's vision of them. The Warcraft games, for example, copied its orcs from Warhammer (only in WC3 did they began to give them a slightly different flavor).
D&D orcs endured. They never went green. Greenish grey at worst. However, since no one still played them as lawful minions of evil, they went chaotic. (That's why you have seemingly aberrant choices in the Great Wheel, like the orcish pantheon in the lawful Acheron.)
Tolkien's orcs are also Tolkien's goblins. The uruk-hai are what D&D would call half-orcs. Peter Jackson didn't wanted to imply the idea of cross-breeding with orcs and chose to make them mud beasts, but well.