luabitop: disabled for Lua 5.3

see failure in http://autobuild.buildroot.net/results/6306c929e9ee05cbb33e4eb6b590166c6554ec21/



Signed-off-by: Francois Perrad <francois.perrad@gadz.org>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>