Include qapi/qmp/qlist.h exactly where needed

This cleanup makes the number of objects depending on qapi/qmp/qlist.h
drop from 4551 (out of 4743) to 16 in my "build everything" tree.

While there, separate #include from file comment with a blank line.

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20180201111846.21846-12-armbru@redhat.com>
diff --git a/block/rbd.c b/block/rbd.c
index a76a5e8..76b9e83 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -21,6 +21,7 @@
 #include "qemu/cutils.h"
 #include "qapi/qmp/qstring.h"
 #include "qapi/qmp/qjson.h"
+#include "qapi/qmp/qlist.h"
 
 /*
  * When specifying the image filename use: