added fix for building non-mpi version -D_PM_WITHOUT_MPI_

Tested on vsh as:
./configure CXX=icpc CC=icc FC=ifort  CFLAGS="-std=c99 -openmp" CXXFLAGS="-openmp -DUSE_PAPI" \
--with-papi=yes  --with-example=yes  -prefix=${INSTALLED_DIR}