SPARC64: implement %fprs dirty bits

Implement %fprs.DU/DL bits.
The FPU sets %fprs.DL and %fprs.DU when values are assigned to %f0-31
and %f32-63 respectively.
Signed-off-by: NTsuneo Saito <tsnsaito@gmail.com>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>