should_ignore_name runs once per directory entry during glob/grep tree
walks and looped over ~57 IGNORE_PATTERNS calling fnmatch per pattern.
Precompute the literal names into a frozenset (O(1)) and the few glob
patterns into one combined compiled regex via fnmatch.translate; per name
it's now one normcase + a set lookup + at most one regex match.
os.path.normcase preserves fnmatch's platform case behavior, so results
are identical (covered by an equivalence test against the old loop).
Fixes#3655.
