std_streambuf.h (_M_buf): is currently used only for basic_filebuf, therefore move...

std_streambuf.h (_M_buf): is currently used only for basic_filebuf, therefore move it there.

2003-04-28  Paolo Carlini  <pcarlini@unitus.it>

	* include/std/std_streambuf.h (_M_buf): is currently
	used only for basic_filebuf, therefore move it there.
	(basic_streambuf(), ~basic_streambuf()): Adjust.
	* include/std/std_fstream.h (_M_buf): Moved here.
	* include/std/std_sstream.h (setbuf): Don't set _M_buf,
	is actually redundant for basic_stringbuf.
	(_M_really_sync): Likewise.
	* include/bits/fstream.tcc (basic_filebuf()): Adjust.
	* include/bits/sstream.tcc (seekoff): Adjust.

From-SVN: r66193