inefficient "ordered" scheduling

[shintaro-iwasaki]

An ordered loop is not optimized well, which causes sometimes a timeout in test/worksharing/for/omp_for_collapse.c if execution streams are oversubscribed.

  #pragma parallel omp for ordered
  for (i = 1; i < 10000; i++) {
    #pragma omp ordered
    comp(i);
  }

Although order is not widely used, it should be optimized by using synchronization primitives.