Add 'smemcoherence' kernel

tests/opencl/flops/kernel.cl

@@ -0,0 +1,13 @@
+__kernel void flops (__global volatile const float *src,
+						 __global volatile float *dst,
+						 __local volatile float *smem)
+{
+  int gid = get_global_id(0);
+  float f = 0.0f;
+  float incr = src[0];
+  __attribute__((opencl_unroll_hint))
+  for (int i = 0; i < 5000; i++) {
+	  f += incr;
+  }
+  dst[gid] = f;
+}