The solution is to update your ancient gcc version on the system. In fact, I am quite surprised that you have such an old version on your 12.04 Ubuntu variant. It should have 4.6.3 by deault.
What you could try is c++0x instead of c++11 and see if that makes it work. You could also fire up the gcc manual by issuing man gcc
and look for the precise option.
Also, while we are it, you could probably simply write this in your qmake project file instead of such raw configurations:
CONFIG += c++11