* hash.c (remhash): Walk chain to splice out to-be-removed entry using an approach similar to what is done in do_weak_tables to splice out lapsed weak entries. This eliminates one extra traversal of the chain as well as consing due to the ldiff call. We use raw pointers obtained using valptr, and direct assignment through *pchain because later cells in a chain are strictly older objects than earlier cells and so so the *pchain = cdr(*pchain) assignment cannot make a generation 1 object point to a generation 0 object.