Make do_constrain_first() independent of t_state

Make do_constrain_first() independent of t_state

This changes the do_constrain_first() function to directly take the
required state data (natoms, x, v, box, lambda[efptBONDED]) as input
instead of a pointer to the full t_state object. This makes subsequent
changes to the t_state object easier.

This also adds some trivial const qualifier for the box matrix in the
constraining functions.

Change-Id: I28b58df45481549cd93076334b0778e23e228154