Adjusting 8-tap filter + prelim edge pixel filter code.

Results with the new filter coefficients compared with the previous
versions are here:
http://www.corp.google.com/~debargha/vp8_results/enhinterp.html (derf)
http://www.corp.google.com/~debargha/vp8_results/enhinterp_hd.html (HD)
Overall, the derf set improves by 0.94% with 8-tap filters while
the HD set improves by 0.58%.

Patch 1: resolving merge conflict

Change-Id: I09db0abdab7b08bb19f86d911de23d2123309748

vp8/common/filter.h

@@ -18,7 +18,15 @@
 #define VP8_FILTER_WEIGHT 128
 #define VP8_FILTER_SHIFT  7
 
+/* whether to use a special filter for edge pixels */
+#define EDGE_PIXEL_FILTER 0
+
 extern const short vp8_bilinear_filters[8][2];
 extern const short vp8_sub_pel_filters[8][INTERP_EXTEND*2];
 
+#if EDGE_PIXEL_FILTER > 0
+#define EDGE_PIXEL_FILTER_EXTEND 2
+extern const short vp8_sub_pel_filters_ns[64][4*EDGE_PIXEL_FILTER_EXTEND*EDGE_PIXEL_FILTER_EXTEND];
+#endif
+
 #endif //FILTER_H