[llvm-porfgen] Allow perf data as input

[llvm-porfgen] Allow perf data as input

This change enables llvm-profgen to take raw perf data as alternative input format. Sometimes we need to retrieve evenets for processes with matching binary. Using perf data as input allows us to retrieve process Ids from mmap events for matching binary, then filter by process id during perf script generation.

Differential Revision: https://reviews.llvm.org/D110793