gnu: allegro@4: Update to 4.4.3.

* gnu/packages/game-development.scm (allegro-4): Update to 4.4.3.
[source]: Remove upstreamed patch.
* gnu/packages/patches/allegro4-mesa-18.2.5-and-later.patch:
Delete file.
* gnu/local.mk (dist_patch_DATA): Remove it.