BUG: set correct platform dependent path for virtual python
BUG: set correct platform dependent path for virtual python

This is a problem discovered by David Cole and Matt McCormick.

blowekamp/SimpleITK,kaspermarstal/SimpleElastix,richardbeare/SimpleITK,richardbeare/SimpleITK,InsightSoftwareConsortium/SimpleITK,blowekamp/SimpleITK,hendradarwin/SimpleITK,InsightSoftwareConsortium/SimpleITK,SimpleITK/SimpleITK,SimpleITK/SimpleITK,SimpleITK/SimpleITK,blowekamp/SimpleITK,InsightSoftwareConsortium/SimpleITK,blowekamp/SimpleITK,kaspermarstal/SimpleElastix,richardbeare/SimpleITK,hendradarwin/SimpleITK,kaspermarstal/SimpleElastix,SimpleITK/SimpleITK,InsightSoftwareConsortium/SimpleITK,richardbeare/SimpleITK,hendradarwin/SimpleITK,richardbeare/SimpleITK,InsightSoftwareConsortium/SimpleITK,blowekamp/SimpleITK,hendradarwin/SimpleITK,kaspermarstal/SimpleElastix,blowekamp/SimpleITK,hendradarwin/SimpleITK,richardbeare/SimpleITK,SimpleITK/SimpleITK,richardbeare/SimpleITK,kaspermarstal/SimpleElastix,SimpleITK/SimpleITK,hendradarwin/SimpleITK,blowekamp/SimpleITK,hendradarwin/SimpleITK,kaspermarstal/SimpleElastix,SimpleITK/SimpleITK,blowekamp/SimpleITK,InsightSoftwareConsortium/SimpleITK,richardbeare/SimpleITK,InsightSoftwareConsortium/SimpleITK,SimpleITK/SimpleITK,hendradarwin/SimpleITK,InsightSoftwareConsortium/SimpleITK,kaspermarstal/SimpleElastix