QMP: add human-readable description to error response

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/qerror.h b/qerror.h
index 9462d5c..09e32b9 100644
--- a/qerror.h
+++ b/qerror.h
@@ -13,6 +13,7 @@
 #define QERROR_H
 
 #include "qdict.h"
+#include "qstring.h"
 #include <stdarg.h>
 
 typedef struct QErrorStringTable {
@@ -32,6 +33,7 @@
 QError *qerror_new(void);
 QError *qerror_from_info(const char *file, int linenr, const char *func,
                          const char *fmt, va_list *va);
+QString *qerror_human(const QError *qerror);
 void qerror_print(const QError *qerror);
 QError *qobject_to_qerror(const QObject *obj);