Sign Select instructions

Author: Maratyszcza

proposals/simd/BinarySIMD.md

@@ -225,3 +225,7 @@ For example, `ImmLaneIdx16` is a byte with values in the range 0-15 (inclusive).
 | `f32x4.convert_i32x4_u`    |    `0xfb`| -                  |
 | `v128.load32_zero`         |    `0xfc`| -                  |
 | `v128.load64_zero`         |    `0xfd`| -                  |
+| `v8x16.signselect`         |  `0xfd7d`| -                  |
+| `v16x8.signselect`         |  `0xfd7e`| -                  |
+| `v32x4.signselect`         |  `0xfd7f`| -                  |
+| `v64x2.signselect`         |  `0xfd94`| -                  |