* gnu/packages/games.scm (irrlicht): Update to 1.8.5.
[source]: Use unmodified Debian patches rather than manually maintain
a custom mash-up.
[arguments]: Add a new 'delete-broken-install-rule phase instead.
Don't explicitly return #t from phases.
* gnu/packages/patches/irrlicht-link-against-needed-libs.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.