Replace libmariadbclient-dev with libmysqlclient-dev.

Some packages (e.g. libgdal-dev) depend on libmysqlclient-dev.
Previously that worked fine with libmariadbclient-dev, but
the libmariadbclient-dev package has changed and it can no
longer fill the dependency on libmysqlclient-dev.

Change-Id: I6645114ceaafe01064bd633184f69c3f0721b9d9
Merge "Replace libmariadbclient-dev with libmysqlclient-dev." into production