namei: new re-written version

namei: new re-written version

This new version:
 * not based on chdir()
 * implemented without recursion (does not depend on stack size)
 * list of directories is stored in allocated memory (the code is
   extendable with new functionality (e.g. show usernames, groupnames,
   selunux contexts, ...).
 * supports long command line options
 * adds a new command line option:
     -n, --nosymlinks    don't follow symlinks

Signed-off-by: Karel Zak <kzak@redhat.com>