Make compatible to libdbi >= 0.9.0

Several functions of libdbi are now deprecated (e.g.: dbi_conn_new) and have been replaced with _r functions (e.g.: dbi_conn_new_r) which now require a dbi_instance passed as a parameter. This patch checks if the version of libdbi is higher or equal than 0.9.0 and iff so, it uses the new _r functions instead of the deprecated ones.