monitor: add support for boolean statistics

The next version of Linux will introduce boolean statistics, which
can only have 0 or 1 values.  Support them in the schema and in
the HMP command.

Suggested-by: Amneesh Singh <natto@weirdnatto.in>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
index ca98df0..e8d6963 100644
--- a/monitor/hmp-cmds.c
+++ b/monitor/hmp-cmds.c
@@ -2337,6 +2337,8 @@
 
         if (stats_value->type == QTYPE_QNUM) {
             monitor_printf(mon, ": %" PRId64 "\n", stats_value->u.scalar);
+        } else if (stats_value->type == QTYPE_QBOOL) {
+            monitor_printf(mon, ": %s\n", stats_value->u.boolean ? "yes" : "no");
         } else if (stats_value->type == QTYPE_QLIST) {
             uint64List *list;
             int i;