The testbuckets none/tests/ppc{32,64} did not build in case the
toolchain did not support -maltivec -mabi=altivec.
This should work now. Fixes BZ #338731


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14566 a5019735-40e9-0310-863c-91ae7b9d1cf9