libgfortran: Adjust bytes_left and pos for access="STREAM".

During tab edits, the pos (position) and bytes_used
Variables were not being set correctly for stream I/O.
Since stream I/O does not have 'real' records, the
format buffer active length must be used instead of
the record length variable.

       PR libgfortran/109358

libgfortran/ChangeLog:

	* io/transfer.c (formatted_transfer_scalar_write): Adjust
	bytes_used and pos variable for stream access.

gcc/testsuite/ChangeLog:

	* gfortran.dg/pr109358.f90: New test.