-> WebPImageReader
Introduce a variant of image-guessing function that returns a reader
directly: WebPGuessImageReader()
Change-Id: I5ddc53024fcf941e33d997b2be6aa1a963d939ab
adds a generic examples/image_dec.[ch] entry point too.
WebPGuessImageType() can be used to infer image type.
Change-Id: I8337e7b6ad91863c9cf118e4791668d2d175079b