PR libfortran/35293
	* io/unix.c (fd_truncate): Fold s->special_file case into
	success case of ftruncate/chsize call instead of the failure case.
	Make failure case actually return failure.  Properly update stream
	pointers on failure.  Call runtime_error for targets without
	neither ftruncate nor chsize where such a call would be needed.

From-SVN: r132888