Merge branch 'jc/ls-files-i-dir'

"git ls-files --exclude=t -i" did not consider anything under t/ as excluded, as it did not pay attention to exclusion of leading paths while walking the index. Other two users of excluded() are also updated. * jc/ls-files-i-dir: dir.c: make excluded() file scope static unpack-trees.c: use path_excluded() in check_ok_to_remove() builtin/add.c: use path_excluded() path_excluded(): update API to less cache-entry centric ls-files -i: micro-optimize path_excluded() ls-files -i: pay attention to exclusion of leading paths