Merge branch 'nd/dir-exclude-cleanup' into maint

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()

dir.c

@@ -564,9 +564,7 @@ void clear_exclude_list(struct exclude_list *el)
 	free(el->excludes);
 	free(el->filebuf);
 
-	el->nr = 0;
-	el->excludes = NULL;
-	el->filebuf = NULL;
+	memset(el, 0, sizeof(*el));
 }
 
 static void trim_trailing_spaces(char *buf)