pub static pathchecked: AtomicUsizeExpand description
Port of mod_export char **pathchecked; from Src/hashtable.c:595.
Cursor into the $path array tracking how far the PATH-hash-on-
first-use machinery has walked. Bumped by hashcmd (exec.c:1042)
after each successful lookup so subsequent hashdir calls only
scan entries we haven’t already cached.
C uses char **pathchecked (pointer into the path[] array); the
Rust port stores an index since $path lives in paramtab and is
re-fetched on each access. Reset to 0 by path reassignment per
Src/hashtable.c:618.