Wide color gamut support for Postprocessors

### Description
I want to load facebook logo image with fresco but when I am setting post processor, image not showing, looking to source code tells that fresco can not handle 16 bit png images, but this only happens when using post processor.

### Reproduction

```
SimpleDraweeView image = findViewById(R.id.YOUR_SIMPLE_DRAWEE_VIEW);
String url = "https://www.facebook.com/images/fb_icon_325x325.png";

ImageRequest imageRequest = ImageRequestBuilder.newBuilderWithSource(Uri.parse(url))
.setPostprocessor(new RoundAsCirclePostprocessor())
.build();

PipelineDraweeController controller = (PipelineDraweeController) Fresco.newDraweeControllerBuilder()
.setImageRequest(imageRequest)
.setOldController(image.getController())
.build();

image.setController(controller);
```
### Additional Information

* Fresco version: 1.9.0
* Platform version: Android 8.0, One plus 5T