[Patch, fortran] PDT bugs PR2 83611 and 83731

[Paul Richard Thomas <paul.richard.thomas@gmail.com>]

This patch adds:
(i) Default initializers for parameterized arrays;
(ii) Fixes ordinary assignment of PDTs by implementing the same deep
copy mechanism as for derived types with allocatable components; and
(iii) Fixes the len parameter checking, which failed where the dummy
type had an assumed parameter.

I have in fact committed this patch as revision 256335 since it is
safe for anything other than PDTs.

2018-01-08  Paul Thomas  <pault@gcc.gnu.org>

    PR fortran/83611
    * decl.c (gfc_get_pdt_instance): If parameterized arrays have
    an initializer, convert the kind parameters and add to the
    component if the instance.
    * trans-array.c (structure_alloc_comps): Add 'is_pdt_type' and
    use it with case COPY_ALLOC_COMP. Call 'duplicate_allocatable'
    for parameterized arrays. Clean up typos in comments. Convert
    parameterized array initializers and copy into the array.
    * trans-expr.c (gfc_trans_scalar_assign): Do a deep copy for
    parameterized types.
    *trans-stmt.c (trans_associate_var): Deallocate associate vars
    as necessary, when they are PDT function results for example.

    PR fortran/83731
    * trans-array.c (structure_alloc_comps): Only compare len parms
    when they are declared explicitly.

2018-01-08  Paul Thomas  <pault@gcc.gnu.org>

    PR fortran/83611
    * gfortran.dg/pdt_15.f03 : Bump count of 'n.data = 0B' to 8.
    * gfortran.dg/pdt_26.f03 : Bump count of '_malloc' to 9.
    * gfortran.dg/pdt_27.f03 : New test.

    PR fortran/83731
    * gfortran.dg/pdt_28.f03 : New test.

Cheers

Paul