[llvm] [BOLT] fix print-mem-data not working (PR #156332)

[Paschalis Mpeis via llvm-commits]

paschalis-mpeis wrote:

Great, thanks for adding a test! Some minor improvements:

Could you use `split-file` to keep the .fdata lines in the same file as the code?

Also, for numbers like `0x137c810`: are those absolute numbers from some other example?
Do they matter for this lit test? If not, we could use dummy values like:
```
4 main 10 4 otherSym 123 1
4 main 10 4 otherSym 456 2
4 main 10 4 otherSym abc 4
```

Maybe a comment right above the split-file region oculd explain that 10 (`0x10`) means attaching the mem profile 4 instructions from main.

https://github.com/llvm/llvm-project/pull/156332