[DAGCombine][X86][AArch64] 'A - (A & (B - 1))' -> 'A & (0 - B)' fold (PR44448)

While we do manage to fold integer-typed IR in middle-end,
we can't do that for the main motivational case of pointers.

There is @llvm.ptrmask() intrinsic which may or may not be helpful,
but i'm not sure it is fully considered canonical yet,
not everything is fully aware of it likely.

https://rise4fun.com/Alive/ZVdp

Name: ptr - (ptr & (alignment-1))  ->  ptr & (0 - alignment)
  %mask = add i64 %alignment, -1
  %bias = and i64 %ptr, %mask
  %r = sub i64 %ptr, %bias
=>
  %highbitmask = sub i64 0, %alignment
  %r = and i64 %ptr, %highbitmask

See
  https://bugs.llvm.org/show_bug.cgi?id=44448
  https://reviews.llvm.org/D71499