[llvm] Add an all-in-one histogram intrinsic, along with lowering for AArch64 (PR #88106)

[Simon Pilgrim via llvm-commits]

RKSimon wrote:

@huntergr-arm This is failing on EXPENSIVE_CHECKS builds - please can you take a look?
https://lab.llvm.org/buildbot/#/builders/16/builds/65450

https://github.com/llvm/llvm-project/pull/88106