vp8: WebP decoding support

VP8L, padding and bounds checks by Pascal Massimino

Reviewed-by: Pascal Massimino <pascal.massimino@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/allcodecs.c

@@ -283,6 +283,7 @@ void avcodec_register_all(void)
     REGISTER_DECODER(VP6F,              vp6f);
     REGISTER_DECODER(VP8,               vp8);
     REGISTER_DECODER(VQA,               vqa);
+    REGISTER_DECODER(WEBP,              webp);
     REGISTER_ENCDEC (WMV1,              wmv1);
     REGISTER_ENCDEC (WMV2,              wmv2);
     REGISTER_DECODER(WMV3,              wmv3);