git add: -u/-A now affects the entire working tree

git add: -u/-A now affects the entire working tree

As promised in 0fa2eb530fb7 (add: warn when -u or -A is used without
pathspec, 2013-01-28), in Git 2.0, "git add -u/-A" that is run
without pathspec in a subdirectory updates all updated paths in the
entire working tree, not just the current directory and its
subdirectories.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>