[llvm] Early exit llvm-bolt when coming across empty data files (PR #176859)

[Paschalis Mpeis via llvm-commits]

https://github.com/paschalis-mpeis commented:

Thanks for the improvement @yashssh.

Can you add a test for the empty profile case and also address the formatting issue?

https://github.com/llvm/llvm-project/pull/176859