codegen: Fix compatibility with Python 2.6
codegen: Fix compatibility with Python 2.6

Python 2.6 does not have a flags parameter.
This is needed for RHEL 6.8.

Signed-off-by: Francois Gouget <6b915da68578f6eb004fe99432b967565fc9be8f@codeweavers.com>
Acked-by: Frediano Ziglio <55d48b080b2e443e395cde84d2c83b135a4ff48e@redhat.com>

fgouget/spice-common,fgouget/spice-common,fgouget/spice-common,fgouget/spice-common