[new] devel/libmpq

Hello,

Here's a new port for a forthcoming update to devilutionX.

libmpq is a library for manipulating MPQ (MoPaQ) archives, which are
used by Blizzard in most of their games (e.g., Diablo, Diablo 2,
StarCraft, WarCraft 3, and World of Warcraft).

Thanks to bcallah@ for the review and updates.

Thanks,
Lucas