tree_entry_interesting(): fix depth limit with overlapping pathspecs

tree_entry_interesting(): fix depth limit with overlapping pathspecs

Suppose we have two pathspecs 'a' and 'a/b' (both are dirs) and depth
limit 1. In current code, pathspecs are checked in input order. When
'a/b' is checked against pathspec 'a', it fails depth limit and
therefore is excluded, although it should match 'a/b' pathspec.

This patch reorders all pathspecs alphabetically, then teaches
tree_entry_interesting() to check against the deepest pathspec first,
so depth limit of a shallower pathspec won't affect a deeper one.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>