[llvm-branch-commits] [BOLT] Use identify_magic instead of .so filename heuristic for shared library detection (PR #190902)

[Amir Ayupov via llvm-branch-commits]

https://github.com/aaupov created https://github.com/llvm/llvm-project/pull/190902

Replace the fragile filename-based check (ends_with(".so")) with
identify_magic()/file_magic::elf_shared_object to reliably detect
shared libraries when filtering pre-aggregated profile data by
build ID.

Test Plan: pre-aggregated-perf-shlib.test