libstdc++: Fix std::print test case for Windows

libstdc++-v3/ChangeLog:

	* src/c++23/print.cc (__write_to_terminal) [_WIN32]: If handle
	does not refer to the console then just write to it using normal
	file I/O.
	* testsuite/27_io/print/2.cc (as_printed_to_terminal): Print
	error message on failure.
	(test_utf16_transcoding): Adjust for as_printed_to_terminal
	modifying its argument.