e auth - move all auth to child process only (e_ckpasswd).
this should fix T6211 ensuring no drivers can cause a segfault at exit
time. this also happens to remove the enlightenment_sys -z option for
openbsd and unifies all the passwd checking into the single
enlightenment_ckpasswd binary util (that has ifdefs for openbsd,
freebsd and linux pam in it).
this simplifies code removing a mess of auth being done in multiple
places, removes special fork vs run 1 exe or a different exe in
different cases making it more maintainable. yes - this requires
enlightenment_ckpasswd to be setuid root, but it already was when it