Revert "buildroot: add global build config settings to enable cgroups and namespaces in the kernel to make it compatible for lxc deployments"

This reverts commit c830ac4b1aa72324b804a31b6c8ca05427d20a5e.
Solved conflict when merge with merge_trunk
Merge branch 'testing'
Merge branch 'testing'
Make it easier to generate executables with debug information and without stripping