Merge branch 'nd/attr-pathspec-in-tree-walk'

The traversal over tree objects has learned to honor ":(attr:label)" pathspec match, which has been implemented only for enumerating paths on the filesystem. * nd/attr-pathspec-in-tree-walk: tree-walk: support :(attr) matching dir.c: move, rename and export match_attrs() pathspec.h: clean up "extern" in function declarations tree-walk.c: make tree_entry_interesting() take an index tree.c: make read_tree*() take 'struct repository *'