cmake (and other software) is quite broken on 10.5 ppc with libgcc7. please see the cmake ticket.
rolling back to libgcc7 is presenly the only known fix. there is a pr referenced in the ticket where I reluctantly propose to do that if no better solution is found. upstream says it's complicated to fix. they have to separate libstdc++ from the libstdc++abi code. Not for the squeamish. Probably few around who could do it. btw, on macports, you cannot force a compiler like that. K
