qerror: Move #include out of qerror.h

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/block/iscsi.c b/block/iscsi.c
index 14e97a6..5f7b60c 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -38,6 +38,7 @@
 #include "qemu/iov.h"
 #include "sysemu/sysemu.h"
 #include "qmp-commands.h"
+#include "qapi/qmp/qstring.h"
 
 #include <iscsi/iscsi.h>
 #include <iscsi/scsi-lowlevel.h>