Configure fails without those.
11 Dec 2008; Vlastimil Babka <caster@gentoo.org> icedtea6-1.2.ebuild, icedtea6-1.3.1-r1.ebuild: Add missing libXtst dep. 01 Dec 2008; Andrew John Hughes <gnu_andrew@member.fsf.org> icedtea6-1.3.1-r1.ebuild icedtea6-1.2.ebuild: Add missing X11 dependencies (libXp, libXt, libXau, libXdmcp)