lib: add support for --action-script in libcriu

Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
lib: Add support for setting new namespace flags via libcriu

Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
lib: Generate pkgconfig file

Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
.git: add cgroup01 to gitignore

Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>