Note: For some reason g++ 4.4 is >200% slower than g++ 4.3 on altivec code.
The same benchmark (bench_gemm) was tested, on the same hardware/OS (G4/Debian testing),
with same CFLAGS. With some code reorganizing I managed to get some minor gain
on 4.4, but I just could not reach 4.3 speed. This is most likely a bug, but I'm waiting
to see if it's fixed on 4.5. I'll look into this a bit more.