Move files common for mysql and mariadb under mysql-common

Because galera library path has to be set in mysql config file,
we create a symlink during install time to make sure that there is
always same path for mysql and mariadb and for all architectures.

Change-Id: Iea3264932ec621d3d7618c5c50cbe47a956fb332
sort the element-deps to please dib-lint

Since I43fd90647acba400cea11c665fb587856514b0ee dib-lint
ensure the elment-deps file is properly sorted.

Change-Id: Ie0347951d99a227fe60530645eeda0f4aa55c325
Merge "sort the element-deps to please dib-lint"
Merge "Move files common for mysql and mariadb under mysql-common"