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

[Jay Foad via llvm-commits]

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@@ -19030,6 +19030,65 @@ will be on any later loop iteration.
 This intrinsic will only return 0 if the input count is also 0. A non-zero input
 count will produce a non-zero result.
 
+'``llvm.experimental.vector.histogram.*``' Intrinsic
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+This is an overloaded intrinsic.
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jayfoad wrote:

```suggestion
These intrinsics are overloaded.
```

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