qemu-config: never call the callback after an error, fix leak

Ensure that the callback to qemu_config_foreach is never called upon
an error, by moving the invocation before the "out" label.

Cc: armbru@redhat.com
Fixes: 3770141139 ("qemu-config: parse configuration files to a QDict", 2021-06-04)
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

util/qemu-config.c

@@ -417,12 +417,12 @@ static int qemu_config_foreach(FILE *fp, QEMUConfigCB *cb, void *opaque,
         return res;
     }
     res = count;
-out:
     if (qdict) {
         cb(group, qdict, opaque, errp);
-        qobject_unref(qdict);
     }
+out:
     loc_pop(&loc);
+    qobject_unref(qdict);
     return res;
 }