remove auto-filter (-af) support and make WebPPictureCopy,
WebPPictureIsView, WebPPictureView, WebPPictureCrop, and
WebPPictureRescale noops.
Change-Id: If39d512cc268a0015298a1138dbc94feb86575e5
this avoids duplicates between these trees and dsp/, e.g., enc/tree.c,
dec/tree.c, making pulling the whole library source tree into one target
possible
BUG=webp:279
Change-Id: I060a614833c7c24ddd37bf641702ae6a5eef1775