make firebird-sdbc an experimental feature

Change-Id: I0f2453e23d18597cfe1ad2a4cd4902b15f0a8f7d
fdo#65108 inter-module includes <>

Change-Id: Ie8ca0b1aa7b56ea1d62c9eed798c56ca78464c44
indentation

Change-Id: Idec97e6b9269cb481428bef8b95aa112197fe866