[AArch64] Optimize cmp chain before legalization

* For case bcmp9, there is extras AND and EXTEND int the chain of OR/XOR,
  which prevent the transform, so enable the optimize before legalization.

* The key IR frag related:
      t37: i32,ch = load<(load (s8) from %ir.4), anyext from i8> t0, t11, undef:i64
        t12: i64 = add t4, Constant:i64<8>
      t38: i32,ch = load<(load (s8) from %ir.5), anyext from i8> t0, t12, undef:i64
    t39: i32 = xor t37, t38
  t40: i64 = any_extend t39
t42: i64 = and t40, Constant:i64<255>

Depends on D138398 to fix combine_setcc_glue

Reviewed By: dmgreen, bcl5980
Differential Revision: https://reviews.llvm.org/D137936