Actually, these messages can be ignored. Apparently you have MPICC installed on your system, and this signals the GPAW setup.py script to attempt to compile GPAW in parallel for your machine. This fails (we don't really expect it to work anyway, as we haven't set it up), but the serial version is still installed first.
So, all should be fine, which you can verify by running the attached small test script, e.g. by dropping it on the Job Manager in VNL, or running "atkpython test_gpaw.py" on the command line.