re PR libstdc++/9825 (filebuf::sputbackc breaks sbumpc)

2003-02-24  Paolo Carlini  <pcarlini@unitus.it>

	PR libstdc++/9825
	* src/fstream.cc
	(basic_filebuf<char/wchar_t>::_M_underflow_common): When
	__bump is true (uflow), always increment the read pointer
	(_M_in_cur) before returning successfully.
	* testsuite/27_io/filebuf_virtuals.cc (test12): Add.

From-SVN: r63378