Update libvpx snapshot to v0.9.7-p1 (Cayuga).

source/libvpx/examples/postproc.txt

 @TEMPLATE decoder_tmpl.c
 Postprocessing Decoder
 ======================
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ INTRODUCTION
 This example adds postprocessing to the simple decoder loop.
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ INTRODUCTION
 
 
 Initializing Postprocessing
 ---------------------------
 You must inform the codec that you might request postprocessing at
 initialization time. This is done by passing the VPX_CODEC_USE_POSTPROC
 flag to `vpx_codec_dec_init`. If the codec does not support
 postprocessing, this call will return VPX_CODEC_INCAPABLE. For
 demonstration purposes, we also fall back to default initialization if
 the codec does not provide support.
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ DEC_INIT
 /* Initialize codec */
 res = vpx_codec_dec_init(&codec, interface, NULL,
                          VPX_CODEC_USE_POSTPROC);
 if(res == VPX_CODEC_INCAPABLE) {
     printf("NOTICE: Postproc not supported by %s\n",
            vpx_codec_iface_name(interface));
-    res = vpx_codec_dec_init(&codec, interface, NULL, 0);
+    res = vpx_codec_dec_init(&codec, interface, NULL, flags);
 }
 if(res)
     die_codec(&codec, "Failed to initialize decoder");
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ DEC_INIT
 
 
 Using Adaptive Postprocessing
 -----------------------------
 VP6 provides "adaptive postprocessing." It will automatically select the
 best postprocessing filter on a frame by frame basis based on the amount
@@ skipping 23 matching lines @@
     if(vpx_codec_control(&codec, VP8_SET_POSTPROC, &pp))
         die_codec(&codec, "Failed to turn off postproc");
 } else if(frame_cnt%30 == 16) {
     vp8_postproc_cfg_t  pp = {VP8_DEBLOCK | VP8_DEMACROBLOCK, 4, 0};
 
     if(vpx_codec_control(&codec, VP8_SET_POSTPROC, &pp))
         die_codec(&codec, "Failed to turn on postproc");
 };
 #endif
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PRE_DECODE