to use sb2 from ubuntu repos you need to change config of waemo target to use qemu-arm instead of sb2-qemu-arm. (two appearances) Libc6 installs with this solution.

and touch /etc/ld.so.conf as its missing

Do I need to manually install libstdc++6-dev 4.7.2? Or can I use the one from the repos?

I installed it manually to be on the safe side, but now I cannot install libuuid1 - postinst fails. Can you please find out the whole process of installing the build environment