64-bit two-step compilation on Ubuntu?

[Sean Eskapp]

I'm trying to get a D2 project to build on Ubuntu through Code::Blocks.
Unfortunately, Code::Blocks doesn't allow the simple one-step compilation that
is default with dmd, so it does compiling and linking in two separate steps.
Unfortunately, this is causing some linker errors, the main one being:

/usr/bin/ld: i386 architecture of input file `obj/Debug/main.o' is
incompatible with i386:x86-64 output

I've tried passing -melf_x86_64 to the linker, and that doesn't change
anything. I'm also trying to pass -m64 to the compilation step, and it doesn't
work. Help?