Fix 1.8.1.x regression that stopped matching "dir" (without
trailing slash) to a directory "dir".
* jc/directory-attrs-regression-fix:
t: check that a pattern without trailing slash matches a directory
dir.c::match_pathname(): pay attention to the length of string parameters
dir.c::match_pathname(): adjust patternlen when shifting pattern
dir.c::match_basename(): pay attention to the length of string parameters
attr.c::path_matches(): special case paths that end with a slash
attr.c::path_matches(): the basename is part of the pathname