'Find template builder and call it.'

def BuildTemplate(self, context=None, output=None):

    context = (context or [])
    context.append(('Arch:%s' % self.GetArch()))
    self.platform = platform.system()
    context.extend([('Platform:%s' % self.platform), ('Target:%s' % self.platform)])
    if ('Target:Linux' in context):
        context.append(self.GetPackageFormat())
    template_path = None
    if output:
        template_path = os.path.join(output, grr_config.CONFIG.Get('PyInstaller.template_filename', context=context))
    builder_obj = self.GetBuilder(context)
    builder_obj.MakeExecutableTemplate(output_file=template_path)
