Hint Rewrite bits_rol bits_ror: ints.

Theorem rolm_rolm:
forall x n1 m1 n2 m2,
Z.divide zwordsize modulus ->
rolm (rolm x n1 m1) n2 m2 =
rolm x (modu (add n1 n2) iwordsize)
(and (rol m1 n2) m2).