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 *'

diff --cc archive.c
Simple merge

diff --cc builtin/checkout.c
Simple merge

diff --cc builtin/grep.c
Simple merge

diff --cc builtin/log.c
Simple merge

diff --cc builtin/ls-tree.c
Simple merge

diff --cc list-objects.c
Simple merge

diff --cc merge-recursive.c
Simple merge

diff --cc revision.c
Simple merge

diff --cc unpack-trees.c
Simple merge