Shared toom evaluation functions

[Niels Möller]

bodrato at mail.dm.unipi.it writes:

> Niels should revive its toom_eval_pm2.c... and use the new functions.

I'm not sure I understand what the function mpn_rsblsh1_n does and why
it's useful here (although I haven't tried very hard to understand
it...).

Anyway, if you know what to do, you can start with
toom_eval_dgr3_pm2.c, which is in the tree.

Regards,
/Niels