Update INSTALL to match the correct current minimum build requirements
Update INSTALL to match the correct current minimum build requirements

lgritz/OpenShadingLanguage,brechtvl/OpenShadingLanguage,lgritz/OpenShadingLanguage,imageworks/OpenShadingLanguage,imageworks/OpenShadingLanguage,brechtvl/OpenShadingLanguage,brechtvl/OpenShadingLanguage,brechtvl/OpenShadingLanguage,lgritz/OpenShadingLanguage,imageworks/OpenShadingLanguage,aconty/OpenShadingLanguage,aconty/OpenShadingLanguage,lgritz/OpenShadingLanguage,aconty/OpenShadingLanguage,brechtvl/OpenShadingLanguage,imageworks/OpenShadingLanguage,aconty/OpenShadingLanguage,lgritz/OpenShadingLanguage,aconty/OpenShadingLanguage,imageworks/OpenShadingLanguage