gnu: irrlicht: Update to 1.8.4.

* gnu/packages/games.scm (irrlicht): Update to 1.8.4.
[arguments]: Delete phase "apply-patch/mesa-10-fix".
[native-inputs]: Remove "patch/mesa-10-fix".
* gnu/packages/patches/irrlicht-mesa-10.patch: Delete file.
* gnu/local.mk (dist_path_DATA): Remove irrlicht patch.