More neon intrinsics. In particular vst2
More neon intrinsics. In particular vst2

Former-commit-id: 74e6ee76ca213d8d507e6fe708d2ce443304d6f2
darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide