Include qapi/qmp/qerror.h exactly where needed

In particular, don't include it into headers.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>
diff --git a/monitor.c b/monitor.c
index 497fed2..aeea2b5 100644
--- a/monitor.c
+++ b/monitor.c
@@ -49,6 +49,7 @@
 #include "sysemu/kvm.h"
 #include "qemu/acl.h"
 #include "sysemu/tpm.h"
+#include "qapi/qmp/qerror.h"
 #include "qapi/qmp/qint.h"
 #include "qapi/qmp/qfloat.h"
 #include "qapi/qmp/qlist.h"