task/mpi: Explicit check for version mismatch
task/mpi: Explicit check for version mismatch

Instead of proceeding to have mpiexec fail or hang,
do an up-front check that the MPI version is the same
on all of the nodes in the test.

Signed-off-by: John Spray <a0ab4ec42db5a70bbcbfc74d8971c0305528d92b@redhat.com>

dreamhost/teuthology,yghannam/teuthology,SUSE/teuthology,t-miyamae/teuthology,zhouyuan/teuthology,ktdreyer/teuthology,ivotron/teuthology,dreamhost/teuthology,ktdreyer/teuthology,ceph/teuthology,SUSE/teuthology,robbat2/teuthology,SUSE/teuthology,yghannam/teuthology,tchaikov/teuthology,caibo2014/teuthology,michaelsevilla/teuthology,ivotron/teuthology,ceph/teuthology,dmick/teuthology,caibo2014/teuthology,robbat2/teuthology,dmick/teuthology,tchaikov/teuthology,t-miyamae/teuthology,dmick/teuthology,zhouyuan/teuthology,michaelsevilla/teuthology