Improved the build flag construction code in the python install method.
Improved the build flag construction code in the python install method.

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