avoid calling putback more than once between reads * liboctave/lo-utils.cc (octave_read_value<double>, (octave_read_value<float>): Save stream position with tellg. On failure, restore stream position with seekg. Avoid calling putback multiple times between stream reads. (octave_read_inf_nan_na, octave_read_float_inf_nan_na): Don't call putback. Make it the caller's responsibility to reset stream positioning on failed reads.