Function dump_available 

pub fn dump_available() -> bool

True iff a year-versioned latex kernel dump is present in the dev tree. Without it the engine raw-loads expl3-code.tex (degraded mode) and the error landscape is dominated by unrelated raw-load cascades — dump-gated tests should SKIP rather than measure the wrong thing. Delegates to the engine’s own dump-name convention so a filename-scheme change cannot make the tests silently self-skip forever.