tracing: Accept different type for synthetic event fields

Make the synthetic event accepts a different type field to record.
However, the size and signed flag must be same.

Link: http://lkml.kernel.org/r/157867235358.17873.61732996461602171.stgit@devnote2Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/trace_events_hist.c

@@ -4110,8 +4110,11 @@ static int check_synth_field(struct synth_event *event,
 
 	field = event->fields[field_pos];
 
-	if (strcmp(field->type, hist_field->type) != 0)
+	if (strcmp(field->type, hist_field->type) != 0) {
+		if (field->size != hist_field->size ||
+		    field->is_signed != hist_field->is_signed)
 			return -EINVAL;
+	}
 
 	return 0;
 }