Update mkgmap to version r2679
Update ruby-cri to version 2.4.0

In addition to bumping version number of package, several other changes were
made:

* This package is licensed under the MIT license. A license file, `LICENSE`, has
  been added.
* A script for checking the currently-installed library version has been added.
* The PKGBUILD itself has been polished. Comments, the `pkgdesc`, and other
  elements have been tweaked.