* fhandler.h (class dev_console): Add members con_mbtowc, con_wctomb,

	* fhandler.h (class dev_console): Add members con_mbtowc, con_wctomb,
	and con_charset.
	(dev_console::str_to_con): Take mbtowc function pointer and charset
	as additional parameters.
	* fhandler_console.cc (fhandler_console::get_tty_stuff): Initialize
	aforementioned new members.  Explain why.
	(dev_console::con_to_str): Remove useless comment.  Call new
	sys_cp_wcstombs function rather than sys_wcstombs.
	(dev_console::str_to_con): Take mbtowc function pointer and charset
	as additional parameters.  Call sys_cp_mbstowcs accordingly.
	(fhandler_console::write_normal): Only initialize f_mbtowc and charset
	once.  Accommodate changed str_to_con.
	* strfuncs.cc (sys_cp_wcstombs): Renamed from sys_wcstombs.  Take
	wctomb function pointer and charset as parameters.  Use throughout.
	(sys_cp_mbstowcs): Take wctomb function pointer and charset as
	parameters instead of codepage.  Remove matching local variables and
	their initialization.
	* wchar.h (ENCODING_LEN): Define as in newlib.
	(__mbtowc): Use mbtowc_p typedef for declaration.
	(wctomb_f): New type.
	(wctomb_p): New type.
	(__wctomb): Declare.
	(__utf8_wctomb): Use wctomb_f typedef for declaration.
	(sys_cp_wcstombs): Move declaration from winsup.h here.
	(sys_wcstombs): Ditto.
	(sys_wcstombs_alloc): Ditto.
	(sys_cp_mbstowcs): Ditto.
	(sys_mbstowcs): Ditto.
	(sys_mbstowcs_alloc): Ditto.
	* winsup.h: Move declaration of sys_FOO functions to wchar.h.  Include
	wchar.h instead.