re PR fortran/83225 (runtime error in transfer.c)

re PR fortran/83225 (runtime error in transfer.c)

2017-12-02  Jerry DeLisle  <jvdelisle@gcc.gnu.org>

	PR libgfortran/83225
	* io/io.h (is_internal_unit): Use the unit_is_internal bit.
	* io/transfer.c (data_transfer_init): Set the bit to true for
	internal umits. Use that bit for checks for internal unit
	initializations.
	* io/unit.c (insert_unit): As a precaution, set the
	internal_unit_kind to zero when a unit structure is first created.

From-SVN: r255362