Don't mess with INFOPATH in ns builds

Don't mess with INFOPATH in ns builds

It's not necessary, and would break if INFOPATH was already set (bug#2791).
Ref also
http://lists.gnu.org/archive/html/emacs-devel/2009-05/msg00035.html
http://lists.gnu.org/archive/html/emacs-devel/2005-06/msg00064.html

* lisp/paths.el (Info-default-directory-list):
* lisp/info.el (info-initialize): For self-contained NS builds, put the
included info/ directory at the front.

* src/nsterm.m (ns_init_paths): Don't mess with INFOPATH.