MAINTAINERS: add missing support status fields

MAINTAINERS: add missing support status fields

This patch adds the "S:" line for areas of the codebase that currently
lack a support status field.

Note that there are a few more areas that are more abstract and do not
correspond to a specific set of files.  They have not been modified.

Cc: Alex Bennée <[email protected]>
Signed-off-by: Stefan Hajnoczi <[email protected]>
Reviewed-by: Thomas Huth <[email protected]>
Reviewed-by: Alex Bennée <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Message-id: 20190301163518[email protected]
Message-Id: <20190301163518[email protected]>
Signed-off-by: Stefan Hajnoczi <[email protected]>