* src/w32font.c (w32font_list_internal): Allow 'ascii-0' charset,
in addition to 'iso10646-1', 'unicode-bmp', and 'unicode-sip'.
This avoids rejecting many font families whose members are shown
by 'font-family-list', in particular 'courier' requested by
info.el. Without this change, many values of ':family' attribute
of a face have no effect on MS-Windows, because they are rejected
due to bogus mismatch of the charset.