To avoid confusion between multiple loops, a new loop field is added to
the gfc_ss (patch 35).
Then we can remove superfluous loop argument in function interfaces:
 - set_vector_loop_bounds (patch 36)
 - gfc_trans_array_constructor (patch 37)
 - gfc_trans_create_temp_array (patch 39)
Patch 38 prepares patch 39 by adding a new variable total_dim which will be
the sum of multiple nested loop dimensions so that the number of loop usages
(through loop.dimen) is reduced.
OK?