[OpenCL] Add `restrict` modifier on buffer arguments
[OpenCL] Add `restrict` modifier on buffer arguments

- Similar to PTX, where 'noalias' is added to help alias analysis. In OpenCL,
  'restrict' is used instead.

ronen/Halide,psuriana/Halide,psuriana/Halide,kgnk/Halide,kgnk/Halide,kgnk/Halide,ronen/Halide,kgnk/Halide,kgnk/Halide,ronen/Halide,kgnk/Halide,psuriana/Halide,psuriana/Halide,psuriana/Halide,ronen/Halide,kgnk/Halide,psuriana/Halide,psuriana/Halide,kgnk/Halide,ronen/Halide,ronen/Halide,ronen/Halide,ronen/Halide