File _multibuild of Package petsc
<multibuild> <package>serial</package> <!-- <package>openmpi</package> --> <package>gnu-openmpi-hpc</package> <package>gnu-mvapich2-hpc</package> </multibuild>
<multibuild> <package>serial</package> <!-- <package>openmpi</package> --> <package>gnu-openmpi-hpc</package> <package>gnu-mvapich2-hpc</package> </multibuild>