The unicity table was mixed with the bddNode table for now
apparent reason. After the hash of some node is computed,
bddnodes[hash] did only contain some random node (not the one
looked for) whose .hash member would point to the actual node with
this hash. So that's a two step lookup. With this patch, we sill
have a two step lookup, but the .hash member have been moved to a
separate array. A consequence is that bddNode is now 16-byte long
(instead of 20) so it will never span across two cache lines.
* src/kernel.h (bddNode): Remove the hash member, and move it...
(bddhash): ... as this new separate table.
* src/kernel.c, src/reorder.c: Adjust all code.
Fix some warnings reported by gcc.
* buddy/src/kernel.c (errorstrings): Mark these as const.
* buddy/src/reorder.c (reorder_gbc): Fix prototype.
(siftTestCmp): Add missing const in cast.
(bdd_reorder_auto): Actually call bdd_reorder_ready().
