[llvm-exegesis] Check perf_branch_entry for field cycles

Summary: Follow up to breakages reported in D77422

Reviewers: ondrasej, gchatelet

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D84076

GitOrigin-RevId: 48c948abeb7dd8a2d022749d1cc1561ddc45d8dc
2 files changed