std_fstream.h (xsputn): Don't call _M_destroy_pback...

2003-07-06  Paolo Carlini  <pcarlini@unitus.it>

	* include/std/std_fstream.h (xsputn): Don't call _M_destroy_pback:
	if output is at all possible (!_M_reading), cannot be active.

	* include/std/std_fstream.h: Tweak comments to doxygen style.

From-SVN: r69001