[M3devel] cm3 -O (cm3cg -O3)

[Tony Hosking]

I've successfully bootstrapped with -O now for

AMD64_DARWIN,
PPC_DARWIN,
I386_DARWIN, and
SOLgnu,

so I think the gcc-based backend is now in much better shape.

The only common target missing here is x86/amd64 linux.

I'll try to get around to those sometime soon.