Lacking actual hardware I tried to re-bootstrap GPRbuild by doing Koji
builds of selected package versions in a specific order. That failed
when it turned out that GPRbuild failed to recognize GCC as a suitable
After lots of trouble and setbacks I finally managed to get a ppc64
emulator installed and working just about well enough that I could
build with RPMbuild and troubleshoot GPRbuild. I now have GPRbuild 2015
built for ppc64, and it seems to be able to rebuild itself.
I had no success with any other emulators, but now I have a good idea
of how to get GPRbuild to find the compiler on other architectures, so
I'm going to try bootstrapping through Koji again.
If I don't run into any more problems, then up-to-date packages may
start to appear soonish.