Show BoolFlag default value in help usage

now that BoolTFlag is gone

flag.go

@@ -624,8 +624,8 @@ func stringifyFlag(f Flag) string {
 	defaultValueString := ""
 	val := fv.FieldByName("Value")
 
-	if val.IsValid() && val.Kind() != reflect.Bool {
-		needsPlaceholder = true
+	if val.IsValid() {
+		needsPlaceholder = val.Kind() != reflect.Bool
 		defaultValueString = fmt.Sprintf(" (default: %v)", val.Interface())
 
 		if val.Kind() == reflect.String && val.String() != "" {

flag_test.go

@@ -14,8 +14,8 @@ var boolFlagTests = []struct {
 	name     string
 	expected string
 }{
-	{"help", "--help\t"},
-	{"h", "-h\t"},
+	{"help", "--help\t(default: false)"},
+	{"h", "-h\t(default: false)"},
 }
 
 func TestBoolFlagHelpOutput(t *testing.T) {