* games/packages/baba-is-you.scm (baba-is-you): Use target-64bit? for
matching.
* games/packages/reus.scm (reus): Same.
* games/packages/the-dark-mod.scm (the-dark-mod-updater): Same.
* games/packages/torchlight2.scm (torchlight2): Same.
* games/packages/unigine.scm (unigine-heaven, unigine-valley): Same.
* games/packages/world-of-goo.scm (world-of-goo): Same.
* games/packages/mini-metro.scm (mini-metro): Add catch-all for other
systems.