4688 getlogin_r shouldn't clobber memory
Reviewed by: Marcel Telka <marcel.telka@nexenta.com>
Reviewed by: Igor Kozhukhov <ikozhukhov@gmail.com>
Reviewed by: Gary Mills <gary_mills@fastmail.fm>
Reviewed by: Toomas Soome <tsoome@me.com>
Approved by: Dan McDonald <danmcd@omniti.com>