No, it's not related. The problem that is causing the buildbot to fail is when compiling with -O2 flag on Linux 64bit. For some reason that I have yet to figure out, the gnuc compiler optimizations invalidates the code in the as_callfunc_x64_gcc.cpp file. I think I've managed to get it to work with returning normal floats or doubles, but it is still failing when returning a POD structure with floats. Like the vector3 structure that you're using in your project.
I believe it is just a minor adjustment that is needed to the code to protect it against the optimizations, but without a way to actually debug the code myself it has been very hard to figure out.