This cleanup makes the number of objects depending on qapi/qmp/qdict.h
drop from 4550 (out of 4743) to 368 in my "build everything" tree.
For qapi/qmp/qobject.h, the number drops from 4552 to 390.
While there, separate #include from file comment with a blank line.
Reviewed-by: Eric Blake <firstname.lastname@example.org>
Reviewed-by: Philippe Mathieu-Daudé <email@example.com>
Signed-off-by: Markus Armbruster <firstname.lastname@example.org>