bugfix: dirlookup() return dirsearch error if any (AFPERR_PARAM).

bugfix: dirlookup() return dirsearch error if any (AFPERR_PARAM).
cname():
we always need to call movecwd, even if we extended the cache eg:
cname dir1\0dir2\0\0 have to chdir to dir1. It wasn't the case if dir2 was not
in the cache.

do the right stuff when the user don't have right access to a directory. Some
calls are unfixable (afp_xxxcomment) or will always fail (afp_delete) but it'd
be ok.