When attempting to emerge xorg-x11 or just luit luit:
!!! All ebuilds that could satisfy "x11-apps/luit" have been masked.
!!! One of the following masked packages is required to complete your request:
- x11-apps/luit-1.1.1::core-gl-kit (masked by: invalid: DEPEND: USE flag 'ppc-aix' referenced in conditional 'ppc-aix?' is not in IUSE)*
(dependency required by "x11-base/xorg-x11-7.4-r3::core-gl-kit" [ebuild])
(dependency required by "xorg-x11" [argument])
For more information, see the MASKED PACKAGES section in the emerge
man page or refer to the Gentoo Handbook.