Make openmp variant false by default.
Make openmp variant false by default.

tmerrick1/spack,tmerrick1/spack,tmerrick1/spack,mfherbst/spack,krafczyk/spack,lgarren/spack,matthiasdiener/spack,matthiasdiener/spack,skosukhin/spack,TheTimmy/spack,LLNL/spack,iulian787/spack,matthiasdiener/spack,mfherbst/spack,krafczyk/spack,TheTimmy/spack,lgarren/spack,mfherbst/spack,lgarren/spack,krafczyk/spack,TheTimmy/spack,mfherbst/spack,mfherbst/spack,skosukhin/spack,TheTimmy/spack,skosukhin/spack,skosukhin/spack,tmerrick1/spack,lgarren/spack,matthiasdiener/spack,EmreAtes/spack,EmreAtes/spack,LLNL/spack,tmerrick1/spack,krafczyk/spack,lgarren/spack,LLNL/spack,iulian787/spack,LLNL/spack,iulian787/spack,iulian787/spack,matthiasdiener/spack,EmreAtes/spack,EmreAtes/spack,iulian787/spack,LLNL/spack,TheTimmy/spack,EmreAtes/spack,skosukhin/spack,krafczyk/spack