(gen_shifty_op): Output a NOP for a shift by 0.

(gen_shifty_op): Output a NOP for a shift by 0.

(find_barrier): New variables si_limit, hi_limit.  Set them depending
on whether we are optimizing.  Set found_hi if the destination is
HImode.
(machine_dependent_reorg): If not optimizing, then change scan to a
note instead of calling delete_insn.

From-SVN: r10937