curve: move taia related functions into own header

Move them into a separate header, structures and inline functions,
since they are more or less independant of curve.h.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
taia: move taia evaluation out of curve.

This is not really related to curve functions, so move it out from
there.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>