fix simple3 sample

hercules_samples/simple3.hir

 fn simple3<1>(a: array(f32, #0), b: array(f32, #0)) -> f32
   zero = constant(f32, 0.0)
   fork = fork(start, #0)
-  id = thread_id(fork)
+  id = thread_id(fork, 0)
   join = join(fork)
   r = return(join, dot_red)
   aval = read(a, position(id))
   bval = read(b, position(id))
   mul = mul(aval, bval)
   dot = add(mul, dot_red)
-  dot_red = reduce(join, zero, dot)
\ No newline at end of file
+  dot_red = reduce(join, zero, dot)