It looks like you have two conflicting installations of MPI. You have one version of Open MPI and you installed another version of MPICH. You probably should uninstall both and try again with just one or the other.
UPDATE:
To summarize the extended comments below, the original poster had some issues with his environmental setup, specifically that the Makefile for the benchmarks was pointing to the wrong mpixcc
and that the C_INCLUDE_PATH
was not set correctly.