Merge branch 'nd/ls-tree-pathspec'

Merge branch 'nd/ls-tree-pathspec'

"git ls-tree" does not support path selection based on negative
pathspecs, but did not error out when negative pathspecs are given.

* nd/ls-tree-pathspec:
  t3102: style modernization
  t3102: document that ls-tree does not yet support negated pathspec
  ls-tree: disable negative pathspec because it's not supported
  ls-tree: remove path filtering logic in show_tree
  tree.c: update read_tree_recursive callback to pass strbuf as base