Git commit 2e827ac "Set MPI_DIR so that centos doesn't have to build MPI. Update the recommended yum packages so that libtldl is present." commented out all OpenMP settings in centos.cfg which given that the configure script says
determine OPENMP_MODE from the OPENMP option
if this option isn't set OPENMP_MODE will default to 'no'
this would mean that the code is not compiled with OpenMP making it impossible to test OpenMP parallelisation using this option list.