[llvm-branch-commits] [BOLT] Support multiple perf data inputs (PR #199324)

[Amir Ayupov via llvm-branch-commits]

https://github.com/aaupov created https://github.com/llvm/llvm-project/pull/199324

Allow -p/-perfdata to accept multiple files as comma-separated and
repeated arguments. Process them with `-perfdata-jobs` (default 4).
Keep YAML/DataReader inputs single-profile only.

Test Plan: Updated pre-aggregated-perf.test and perf_test