hygiene, make sure pats array is never referenced with negative offset
hygiene, PEBKAC, free all resources upon failing to read pats in __read_pats()
hygiene, do not try posix_fadvise() on negative file descriptors
hygiene, check *alloc return values
hygiene, check *alloc return values in interning system

This is separate from the previous commit to facilitate cross-project
cherry-picking.
hygiene, eliminate unused value warnings
hygiene, rid for-loop that isn't one, use if instead
Merge branch 'code/hygiene'

* code/hygiene:
  hygiene, rid for-loop that isn't one, use if instead
  hygiene, eliminate unused value warnings
  hygiene, check *alloc return values in interning system
  hygiene, check *alloc return values
  hygiene, do not try posix_fadvise() on negative file descriptors
  hygiene, PEBKAC, free all resources upon failing to read pats in __read_pats()
  hygiene, make sure pats array is never referenced with negative offset