flops: unroll by 16

tests/opencl/flops/kernel.cl

@@ -5,7 +5,7 @@ __kernel void flops (__global volatile const float *src,
   int gid = get_global_id(0);
   float f = 0.0f;
   float incr = src[0];
-  __attribute__((opencl_unroll_hint))
+  __attribute__((opencl_unroll_hint(16)))
   for (int i = 0; i < 5000; i++) {
 	  f += incr;
   }