Add FcTypeUnknown to FcType to avoid comparison of constant -1

Add FcTypeUnknown to FcType to avoid comparison of constant -1

This change reverts 9acc14c34a372b54f9075ec3611588298fb2a501
because it doesn't work as expected when building
with -fshort-enums which is default for older arms ABIs

Thanks for pointing this out, Thomas Klausner, Valery Ushakov, and Martin Husemann