[llvm] [LV] Enable Histogram autovectorization by default (PR #158292)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

It would probably be good to add some micro benchmarks for loops with histograms to https://github.com/llvm/llvm-test-suite/tree/main/MicroBenchmarks/LoopVectorization, to make it easier to evaluate performance

https://github.com/llvm/llvm-project/pull/158292