qapi: Improve error position for bogus invalid "Returns" section

When something other than a command has a "Returns" section, the error
message points to the beginning of the definition comment.  Point to
the "Returns" section instead.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20240216145841.2099240-7-armbru@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
2 files changed