[llvm] [CodeGen][NewPM] Port `machine-block-freq` to new pass manager (PR #98317)

[Matt Arsenault via llvm-commits]

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+; RUN: llc -mtriple=x86_64-linux-gnu -stop-after=x86-isel %s -o - | llc --passes='print<machine-block-freq>' -x mir -o - 2>&1 | FileCheck %s
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arsenm wrote:

Use -filetype=null if you are just discarding the output.

Is there much point to starting with IR if you're just codegening it to get the MIR? 

https://github.com/llvm/llvm-project/pull/98317