I believe this port is really an external compiler definition, not really a cross-compiler in the sense that devel/powerpc64-gcc is that targets a specific arch.
Please see the following bugs to illustrate my point that "x" in "xtoolchain" refers to "external" (external to world) not "cross" necessarily:
I would propose the pkg-descr be changed to state this is an external compiler definition for building FreeBSD base.
Sorry this got lost. I don't know why it wasn't assigned to me as the maintainer.
pkg-descr seems to already do this. It says:
Pre seeded cross toolchain definition to cross build FreeBSD base
In any case, I plan to remove these ports in the near future, merging them with the associated llvm ports.