Change the warp filter to use real 8-tap

The warp filter for the (0,1) case is changed to use a real
8-tap filter.

Improves coding efficiency.

BDRATE on lowres:
-0.772% (up from -0.633%) with --enable-global-motion
-1.124% (up from -1.001%) with --enable-warped-motion

Change-Id: I296efe36dbc72a7af74773b71b445f19a2aa7205
diff --git a/av1/common/warped_motion.c b/av1/common/warped_motion.c
index 6056914..92dd659 100644
--- a/av1/common/warped_motion.c
+++ b/av1/common/warped_motion.c
@@ -449,38 +449,38 @@
   { 0, - 1,   4, 127, - 3, 1, 0, 0 }, { 0, - 1,   2, 128, - 1, 0, 0, 0 },
 
   // [0, 1)
-  { 0, 0,   0, 128,   0,   0, 0, 0 }, { 0, 0, - 1, 128,   2, - 1, 0, 0 },
-  { 0, 1, - 3, 127,   4, - 1, 0, 0 }, { 0, 1, - 4, 126,   6, - 2, 1, 0 },
-  { 0, 1, - 5, 126,   8, - 3, 1, 0 }, { 0, 1, - 6, 125,  11, - 4, 1, 0 },
-  { 0, 1, - 7, 124,  13, - 4, 1, 0 }, { 0, 2, - 8, 123,  15, - 5, 1, 0 },
-  { 0, 2, - 9, 122,  18, - 6, 1, 0 }, { 0, 2, -10, 121,  20, - 6, 1, 0 },
-  { 0, 2, -11, 120,  22, - 7, 2, 0 }, { 0, 2, -12, 119,  25, - 8, 2, 0 },
-  { 0, 3, -13, 117,  27, - 8, 2, 0 }, { 0, 3, -13, 116,  29, - 9, 2, 0 },
-  { 0, 3, -14, 114,  32, -10, 3, 0 }, { 0, 3, -15, 113,  35, -10, 2, 0 },
-  { 0, 3, -15, 111,  37, -11, 3, 0 }, { 0, 3, -16, 109,  40, -11, 3, 0 },
-  { 0, 3, -16, 108,  42, -12, 3, 0 }, { 0, 4, -17, 106,  45, -13, 3, 0 },
-  { 0, 4, -17, 104,  47, -13, 3, 0 }, { 0, 4, -17, 102,  50, -14, 3, 0 },
-  { 0, 4, -17, 100,  52, -14, 3, 0 }, { 0, 4, -18,  98,  55, -15, 4, 0 },
-  { 0, 4, -18,  96,  58, -15, 3, 0 }, { 0, 4, -18,  94,  60, -16, 4, 0 },
-  { 0, 4, -18,  91,  63, -16, 4, 0 }, { 0, 4, -18,  89,  65, -16, 4, 0 },
-  { 0, 4, -18,  87,  68, -17, 4, 0 }, { 0, 4, -18,  85,  70, -17, 4, 0 },
-  { 0, 4, -18,  82,  73, -17, 4, 0 }, { 0, 4, -18,  80,  75, -17, 4, 0 },
-  { 0, 4, -18,  78,  78, -18, 4, 0 }, { 0, 4, -17,  75,  80, -18, 4, 0 },
-  { 0, 4, -17,  73,  82, -18, 4, 0 }, { 0, 4, -17,  70,  85, -18, 4, 0 },
-  { 0, 4, -17,  68,  87, -18, 4, 0 }, { 0, 4, -16,  65,  89, -18, 4, 0 },
-  { 0, 4, -16,  63,  91, -18, 4, 0 }, { 0, 4, -16,  60,  94, -18, 4, 0 },
-  { 0, 3, -15,  58,  96, -18, 4, 0 }, { 0, 4, -15,  55,  98, -18, 4, 0 },
-  { 0, 3, -14,  52, 100, -17, 4, 0 }, { 0, 3, -14,  50, 102, -17, 4, 0 },
-  { 0, 3, -13,  47, 104, -17, 4, 0 }, { 0, 3, -13,  45, 106, -17, 4, 0 },
-  { 0, 3, -12,  42, 108, -16, 3, 0 }, { 0, 3, -11,  40, 109, -16, 3, 0 },
-  { 0, 3, -11,  37, 111, -15, 3, 0 }, { 0, 2, -10,  35, 113, -15, 3, 0 },
-  { 0, 3, -10,  32, 114, -14, 3, 0 }, { 0, 2, - 9,  29, 116, -13, 3, 0 },
-  { 0, 2, - 8,  27, 117, -13, 3, 0 }, { 0, 2, - 8,  25, 119, -12, 2, 0 },
-  { 0, 2, - 7,  22, 120, -11, 2, 0 }, { 0, 1, - 6,  20, 121, -10, 2, 0 },
-  { 0, 1, - 6,  18, 122, - 9, 2, 0 }, { 0, 1, - 5,  15, 123, - 8, 2, 0 },
-  { 0, 1, - 4,  13, 124, - 7, 1, 0 }, { 0, 1, - 4,  11, 125, - 6, 1, 0 },
-  { 0, 1, - 3,   8, 126, - 5, 1, 0 }, { 0, 1, - 2,   6, 126, - 4, 1, 0 },
-  { 0, 0, - 1,   4, 127, - 3, 1, 0 }, { 0, 0, - 1,   2, 128, - 1, 0, 0 },
+  { 0,  0,   0, 128,   0,   0,  0,  0}, { 0,  1,  -2, 128,   2,  -1,  0,  0},
+  { 0,  1,  -3, 127,   4,  -2,  1,  0}, { 0,  1,  -5, 127,   6,  -2,  1,  0},
+  { 0,  2,  -6, 126,   8,  -3,  1,  0}, {-1,  2,  -7, 126,  11,  -4,  2, -1},
+  {-1,  3,  -8, 125,  13,  -5,  2, -1}, {-1,  3, -10, 124,  16,  -6,  3, -1},
+  {-1,  4, -11, 123,  18,  -7,  3, -1}, {-1,  4, -12, 122,  20,  -7,  3, -1},
+  {-1,  4, -13, 121,  23,  -8,  3, -1}, {-2,  5, -14, 120,  25,  -9,  4, -1},
+  {-1,  5, -15, 119,  27, -10,  4, -1}, {-1,  5, -16, 118,  30, -11,  4, -1},
+  {-2,  6, -17, 116,  33, -12,  5, -1}, {-2,  6, -17, 114,  35, -12,  5, -1},
+  {-2,  6, -18, 113,  38, -13,  5, -1}, {-2,  7, -19, 111,  41, -14,  6, -2},
+  {-2,  7, -19, 110,  43, -15,  6, -2}, {-2,  7, -20, 108,  46, -15,  6, -2},
+  {-2,  7, -20, 106,  49, -16,  6, -2}, {-2,  7, -21, 104,  51, -16,  7, -2},
+  {-2,  7, -21, 102,  54, -17,  7, -2}, {-2,  8, -21, 100,  56, -18,  7, -2},
+  {-2,  8, -22,  98,  59, -18,  7, -2}, {-2,  8, -22,  96,  62, -19,  7, -2},
+  {-2,  8, -22,  94,  64, -19,  7, -2}, {-2,  8, -22,  91,  67, -20,  8, -2},
+  {-2,  8, -22,  89,  69, -20,  8, -2}, {-2,  8, -22,  87,  72, -21,  8, -2},
+  {-2,  8, -21,  84,  74, -21,  8, -2}, {-2,  8, -22,  82,  77, -21,  8, -2},
+  {-2,  8, -21,  79,  79, -21,  8, -2}, {-2,  8, -21,  77,  82, -22,  8, -2},
+  {-2,  8, -21,  74,  84, -21,  8, -2}, {-2,  8, -21,  72,  87, -22,  8, -2},
+  {-2,  8, -20,  69,  89, -22,  8, -2}, {-2,  8, -20,  67,  91, -22,  8, -2},
+  {-2,  7, -19,  64,  94, -22,  8, -2}, {-2,  7, -19,  62,  96, -22,  8, -2},
+  {-2,  7, -18,  59,  98, -22,  8, -2}, {-2,  7, -18,  56, 100, -21,  8, -2},
+  {-2,  7, -17,  54, 102, -21,  7, -2}, {-2,  7, -16,  51, 104, -21,  7, -2},
+  {-2,  6, -16,  49, 106, -20,  7, -2}, {-2,  6, -15,  46, 108, -20,  7, -2},
+  {-2,  6, -15,  43, 110, -19,  7, -2}, {-2,  6, -14,  41, 111, -19,  7, -2},
+  {-1,  5, -13,  38, 113, -18,  6, -2}, {-1,  5, -12,  35, 114, -17,  6, -2},
+  {-1,  5, -12,  33, 116, -17,  6, -2}, {-1,  4, -11,  30, 118, -16,  5, -1},
+  {-1,  4, -10,  27, 119, -15,  5, -1}, {-1,  4,  -9,  25, 120, -14,  5, -2},
+  {-1,  3,  -8,  23, 121, -13,  4, -1}, {-1,  3,  -7,  20, 122, -12,  4, -1},
+  {-1,  3,  -7,  18, 123, -11,  4, -1}, {-1,  3,  -6,  16, 124, -10,  3, -1},
+  {-1,  2,  -5,  13, 125,  -8,  3, -1}, {-1,  2,  -4,  11, 126,  -7,  2, -1},
+  { 0,  1,  -3,   8, 126,  -6,  2,  0}, { 0,  1,  -2,   6, 127,  -5,  1,  0},
+  { 0,  1,  -2,   4, 127,  -3,  1,  0}, { 0,  0,  -1,   2, 128,  -2,  1,  0},
 
   // [1, 2)
   { 0, 0, 0,   0, 128,   0,   0, 0 }, { 0, 0, 0, - 1, 128,   2, - 1, 0 },