Added generalized rule (x + c) ^ 0x7F...F -> (0x7F...F - c) - x.
Added local optimization (x | c) + -c -> x & ~c.
Added local optimization (c - x) ^ 0x7F...F -> x + (0x7F...F - c).
tailrec: fix recently introduced bug for unused parameters
combo: fix corner case with multiple opcodes in a partition

This could result in blocks getting asked for their block, which
happened in firm-testsuite/opt/combo10.c