host-qemu: needs host-python

host-qemu: needs host-python

Fixes:
http://autobuild.buildroot.net/results/e58/e58a0d7d5c084be000ae7d5b3821cd68d6639aab/
http://autobuild.buildroot.net/results/624/62425cfdd4270bf1a9b15bd57490478b1c04c720/
http://autobuild.buildroot.net/results/d18/d189d7f75ffbb3349b68a5c312b14ea5638bb903/
http://autobuild.buildroot.net/results/7d3/7d386322cec452ee636adb20be0c1a31f38385fc/

And many more.

Just like qemu for the target, host-qemu needs python (2.x) on the host.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>