Since we use the OpenType versions of Uniscribe functions, we are
relying on that version of the WINNT API. Otherwise, usp10.h will hide
those symbols.
Previously was failing to match fonts that didn't support CHARSET_ANSI.
There still remains a problem with the Uniscribe backend, in that if a
font with the same family name is installed, and is newer, the native
one is preferred over the font we provide. Fixing it requires rewriting
the name table with a unique family name...
Also remove shaper_options argument to hb_shape_full(). That was
unused and for "future". Let it go.
More shaper API coming in preparation for plan/planned API.