gnu: mariadb: Split into out, lib and dev.

gnu: mariadb: Split into out, lib and dev.

* gnu/packages/databases.scm (mariadb): Split into out, lib and dev.
(perl-dbd-mysql, python-mysqlclient): Adjust dependencies.
* gnu/packages/bioinformatics.scm (kentutils): Adjust dependencies.
* gnu/packages/cran.scm (r-rmysql): Adjust dependencies.
* gnu/packages/emacs-xyz.scm (emacs-emacsql): Adjust dependencies.
* gnu/packages/kodi.scm (kodi): Adjust dependencies.
* gnu/packages/qt.scm (qt, qtbase): Adjust dependencies.
* gnu/packages/ruby.scm (ruby-mysql2): Adjust dependencies.