python: uses fork(), only available on MMU platforms
Fixes
http://autobuild.buildroot.org/results/1738a8b09b04d2b2fc1de6d1ff5eb0363fed6348/build-end.log
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>