[Patch, fortran] PR71880 - pointer to allocatable character

[Paul Richard Thomas]

Committed as revision 265353.

> Not quite fixed. The lhs character length doesn't get set and so it
> fails at runtime. I will commit the patch as 'obvious'.
>
> Paul
>
> 2018-10-19  Paul Thomas  <pault@gcc.gnu.org>
>
>     PR fortran/71880
>     * trans-expr.c (gfc_trans_pointer_assignment): Set the string
>     length for array valued deferred length lhs.
>
> 2018-10-19  Paul Thomas  <pault@gcc.gnu.org>
>
>     PR fortran/71880
>     * gfortran.dg/deferred_character_31.f90 : New test.