[llvm] [BOLT] Use new assembler directives for EH table emission (PR #116294)

[Maksim Panchenko via llvm-commits]

maksfb wrote:

> Do you have an example (textual) of the old VS new API? That would help me reviewing. Thanks!

The assembler directive is:
```
  .uleb128 .L2 - .L1
```

More details in the ABI diff: https://github.com/llvm/llvm-project/commit/d09b416943fec535f73950b0954e0fcd17719a75

https://github.com/llvm/llvm-project/pull/116294