tstools: uses fork() therefore needs MMU
Fixes:
http://autobuild.buildroot.org/results/4f6/4f611e085a3e21319a98f5383adf2caac77a0bd6/
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>