Enable CVS (Concurrent Versions System) integration

Packages describing “cvs” as local USE flag

Package “cvs” Flag Description
app-portage/layman Support dev-vcs/cvs based overlays
sys-devel/gettext When running `autopoint`, use cvs to store the internal development files; this requires cvs at runtime, but will be faster/smaller than raw archives

All packages providing a “cvs” USE flag (4)