[llvm] [llvm-objdump] Fix mcpuHelp() memory leak (PR #172525)

[Ruoyu Qiu via llvm-commits]

cabbaken wrote:

@jh7370 
Apologies for the oversight in my previous PR. I have addressed the memory leak in this update. Could you please review the fix?

https://github.com/llvm/llvm-project/pull/172525