As the UAPI headers start to appear in distros, we need to avoid
outdated versions of struct clone_args to be able to test modern
features, named "struct __clone_args". Additionally update the struct
size macro names to match UAPI names.
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/lkml/20200921075432.u4gis3s2o5qrsb5g@wittgenstein/Signed-off-by: Kees Cook <keescook@chromium.org>