sstream.tcc (pbackfail): Implement correctly 27.7.1.3/2, bullet 2...

sstream.tcc (pbackfail): Implement correctly 27.7.1.3/2, bullet 2...

2004-10-01  Paolo Carlini  <pcarlini@suse.de>

	* include/bits/sstream.tcc (pbackfail): Implement correctly
	27.7.1.3/2, bullet 2: if mode & ios_base::out is false do not
	write in the buffer.
	* testsuite/27_io/basic_stringbuf/pbackfail/char/1.cc: New.
	* testsuite/27_io/basic_stringbuf/pbackfail/char/2.cc: Likewise.
	* testsuite/27_io/basic_stringbuf/pbackfail/wchar_t/1.cc: Likewise.
	* testsuite/27_io/basic_stringbuf/pbackfail/wchar_t/2.cc: Likewise.
	* testsuite/27_io/basic_istream/putback/char/1.cc: Tweak consistently.

From-SVN: r88407