improve construction of the original schedule

improve construction of the original schedule

The patch builds the original schedule based on the now optimized scattering
dimension instead of building one based on the loop index only.

The implementation is simpler and catches more cases where the original schedule
and the transformed schedule are the same, such as the one below:

for (i = 0; i < 1000; i++)
{
  Temp = F[i];
  for (j = 0; j < 1000; j++)
 {
    D[j] = E[j]  * Temp;
    A[i][j] = A[i][j]  + B[i][j] * C[i][j] - D[j] ;
  }
  D[i] = E[i] * F[i];
}

  * graphite-sese-to-poly.c (build_scop_original_schedule): Call
  isl_union_map_add_map on every pbb->schedule.

From-SVN: r230191