[llvm] [benchmark] Support Linux/sparc64 /proc/cpuinfo (PR #125503)

[Mircea Trofin via llvm-commits]

mtrofin wrote:

Can you please make this change in the google/benchmark repo and link the githash in your commit message - it will help the person that will later sync this fork. Thanks.

https://github.com/llvm/llvm-project/pull/125503