qmp: Eliminate silly QERR_QMP_* macros

qmp: Eliminate silly QERR_QMP_* macros

The QERR_ macros are leftovers from the days of "rich" error objects.

QERR_QMP_BAD_INPUT_OBJECT, QERR_QMP_BAD_INPUT_OBJECT_MEMBER,
QERR_QMP_EXTRA_MEMBER are used in just one place now, except for one
use that has crept into qobject-input-visitor.c.

Drop these macros, to make the (bad) error messages more visible.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <1488544368-30622-10-git-send-email-armbru@redhat.com>