config: Add -s option to run only specified sections
This commit adds -s option which allows you to specify only certain
sections from the config file to be run. The '-s' argument can be
specified multiple times to allow multiple sections to be run.
The options are still carried between section, that includes the
sections which are not going to be run.
Update README.config-sections as well.
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>