Function bypass_llc_locks_active 

pub fn bypass_llc_locks_active() -> bool

True when KTSTR_BYPASS_LLC_LOCKS is set to a NON-EMPTY value.

Centralises the bypass check used at 7 reader sites: vmm/builder.rs:1199, cli/kernel_build/build.rs:102 + :488 (the latter the inverse !bypass_llc_locks_active() form), bin/cargo_ktstr/kernel/mod.rs:720, bin/cargo_ktstr/misc/shell.rs:181, and bin/ktstr.rs:652 + :1267. All sites previously spelled the same .ok().is_some_and(|v| !v.is_empty()) inline; centralising eliminates the drift hazard and matches the no_perf_mode_active shape so the empty-string contract is uniformly enforced.

Set via --bypass-llc-locks CLI flag or KTSTR_BYPASS_LLC_LOCKS=1 direct export. Empty (KTSTR_BYPASS_LLC_LOCKS= from a Docker --env pass-through without value) does NOT activate per the empty-as-unset contract — preventing a stray export from silently disabling LLC flock contention enforcement in CI.