demos/font_features.c: Support PangoWin32 Font as well

Also support PangoWin32 fonts for the font features demo, which will
enable running on Windows even if PangoFT support is not enabled or is
unused.

Check for PangoWin32 as well in configure to see whether the font
features demo will be built.  If either PangoFT2 or PangoWin32 is found
along with HarfBuzz, build the font features demo.
5 jobs for wip/fanc999/fontchooser.win32 in 6 minutes and 4 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Build
passed #274721
fedora-x86_64

00:03:46

passed #274722
win32
msys2-mingw32

00:06:03

 
  Flatpak
manual #274723
allowed to fail manual
flatpak-manual:demo
manual #274725
allowed to fail manual
flatpak-manual:icon-browser
manual #274724
allowed to fail manual
flatpak-manual:widget-factory