去掉@available的使用，防止Xcode9以下编译失败

TZImagePickerController/TZImagePickerController/TZImagePickerController.m

@@ -118,7 +118,7 @@
 
 - (void)configBarButtonItemAppearance {
     UIBarButtonItem *barItem;
-    if (@available(iOS 9.0, *)) {
+    if (iOS9Later) {
         barItem = [UIBarButtonItem appearanceWhenContainedInInstancesOfClasses:@[[TZImagePickerController class]]];
     } else {
         barItem = [UIBarButtonItem appearanceWhenContainedIn:[TZImagePickerController class], nil];

TZImagePickerController/TZImagePickerController/TZPhotoPickerController.m

@@ -59,7 +59,7 @@ static CGFloat itemMargin = 5;
         }
         _imagePickerVc.navigationBar.tintColor = self.navigationController.navigationBar.tintColor;
         UIBarButtonItem *tzBarItem, *BarItem;
-        if (@available(iOS 9.0, *)) {
+        if (iOS9Later) {
             tzBarItem = [UIBarButtonItem appearanceWhenContainedInInstancesOfClasses:@[[TZImagePickerController class]]];
             BarItem = [UIBarButtonItem appearanceWhenContainedInInstancesOfClasses:@[[UIImagePickerController class]]];
         } else {