Merge branch 'nd/dir-exclude-cleanup'

Merge branch 'nd/dir-exclude-cleanup'

The "exclude_list" structure has the usual "alloc, nr" pair of
fields to be used by ALLOC_GROW(), but clear_exclude_list() forgot
to reset 'alloc' to 0 when it cleared 'nr'to discard the managed
array.

* nd/dir-exclude-cleanup:
  dir.c: clean the entire struct in clear_exclude_list()