Use correct variant syntax to build zfp (#5099)
Use correct variant syntax to build zfp (#5099)

`h5z-zfp` now  builds zfp with correct bit stream word size; the syntax of the variant declaration did not work in previous versions of spack but does now
LLNL/spack,TheTimmy/spack,EmreAtes/spack,matthiasdiener/spack,tmerrick1/spack,TheTimmy/spack,skosukhin/spack,lgarren/spack,mfherbst/spack,TheTimmy/spack,TheTimmy/spack,EmreAtes/spack,LLNL/spack,krafczyk/spack,LLNL/spack,iulian787/spack,EmreAtes/spack,matthiasdiener/spack,TheTimmy/spack,iulian787/spack,tmerrick1/spack,skosukhin/spack,iulian787/spack,matthiasdiener/spack,mfherbst/spack,krafczyk/spack,lgarren/spack,mfherbst/spack,skosukhin/spack,lgarren/spack,matthiasdiener/spack,krafczyk/spack,mfherbst/spack,matthiasdiener/spack,lgarren/spack,EmreAtes/spack,LLNL/spack,lgarren/spack,mfherbst/spack,skosukhin/spack,krafczyk/spack,tmerrick1/spack,iulian787/spack,tmerrick1/spack,LLNL/spack,krafczyk/spack,tmerrick1/spack,EmreAtes/spack,iulian787/spack,skosukhin/spack