qapi: convert screendump

Next commits will update devices to propagate errors.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
diff --git a/hmp.h b/hmp.h
index 8e7838c..48b9c59 100644
--- a/hmp.h
+++ b/hmp.h
@@ -72,5 +72,6 @@
 void hmp_getfd(Monitor *mon, const QDict *qdict);
 void hmp_closefd(Monitor *mon, const QDict *qdict);
 void hmp_send_key(Monitor *mon, const QDict *qdict);
+void hmp_screen_dump(Monitor *mon, const QDict *qdict);
 
 #endif