message: use the system compiler used to build MPI for the MPI tests
diff: @@ -91,10 +91,12 @@ pipeline {
  }
  stage('Non-windows interface tests with MPI') {
  agent { label 'linux' }
  + /* use system default compiler used to build MPI
  environment {
  OMPI_CXX = "${env.CXX}"
  MPICH_CXX = "${env.CXX}"
  }
  + */
  steps {
  setupCC("${env.MPICXX}")
  sh "echo STAN_MPI=true >> make/local"
  