Removed -plugin-sql-odbc from Mac OS 10.10 configuration

Some headers that ODBC is using are missing from 10.9 –
and 10.10 SDK. These headers were included in 10.8 SDK
but after that those has been dropped out.

Change-Id: I60179f5cd75704800a5b41de44e7c71be49df76d
Reviewed-by: Akseli Salovaara <akseli.salovaara@digia.com>