0731567a31
Due to delayed decision for ADD/SUB relocations, RISCV and LoongArch may go slow fragment walk path with available layout. When RISCV (or LoongArch in the future) don't need insert nops, that means relax is disabled. With available layout and not needing insert nops, the size of AlignFragment should be a constant. So we can add it to Displacement for folding A-B.