x11/i3lock-color: don't use CONFIGURE_TARGET

Don't hardcode the usage of CONFIGURE_TARGET and let gmake decide
where it will build everything,

This is in preparation of the update of config.guess and config.sub
we will use vanilla version so when we will ask for
amd64-portbld-freebsd14.0
it will reply
x86-64-portbld-freebsd14.0