[llvm] [BOLT][DWARF][NFC] Add parallelization for processing of DWO debug information (PR #100282)

[Amir Ayupov via llvm-commits]

aaupov wrote:

> I wonder if we can modify bolt/test/lit.local.cfg to add common llvm-bolt flags. So we don't have to copy past the same option everythere. @aaupov WDYT?

If you add a top-level test folder (e.g. `bolt/test/debug`) and move relevant tests there, I'm fine with defining common BOLT flags used in those tests in lit.local.cfg.

https://github.com/llvm/llvm-project/pull/100282