qjson.h: include compiler.h for GCC_FMT_ATTR

Signed-off-by: Alon Levy <alevy@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

qjson.h

@@ -15,6 +15,7 @@
 #define QJSON_H
 
 #include <stdarg.h>
+#include "compiler.h"
 #include "qobject.h"
 #include "qstring.h"