File _multibuild of Package john

<multibuild>
  <package>avx</package>
  <package>avx512</package>
  <package>openmpi1</package>
  <package>openmpi2</package>
  <package>openmpi2-avx</package>
  <package>openmpi3</package>
  <package>openmpi4</package>
</multibuild>