HDF5 module will not build in non-MPI mode

abadiel @ 41r100-pcf-0001 : /tmp/darshan-3.2.1/darshan-runtime $ make
gcc -DDARSHAN_CONFIG_H=\"darshan-runtime-config.h\" -I . -I. -I./../ -g -O2 -I/opt/codac/hdf5/include  -D_LARGEFILE64_SOURCE -shared -fpic -DPIC -DDARSHAN_PRELOAD -c lib/darshan-hdf5.c -o lib/darshan-hdf5.po
lib/darshan-hdf5.c: In function ‘H5Fcreate’:
lib/darshan-hdf5.c:177:27: error: ‘MPI_COMM_WORLD’ undeclared (first use in this function)
             MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
                           ^
lib/darshan-hdf5.c:177:27: note: each undeclared identifier is reported only once for each function it appears in
lib/darshan-hdf5.c: In function ‘H5Fopen’:
lib/darshan-hdf5.c:236:27: error: ‘MPI_COMM_WORLD’ undeclared (first use in this function)
             MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
                           ^
make: *** [lib/darshan-hdf5.po] Error 1
Reported by Lana Abadie.