do_fork is declared as:
struct task_struct *do_fork(unsigned long clone_flags,
                            unsigned long stack_start,
                            struct pt_regs *regs,
                            unsigned long stack_size,
                            int *parent_tidptr,
                            int *child_tidptr)
ie. parent_tidptr is out4 and child_tidptr is out5, but
the comments in clone2 were suggesting otherwise.
So, we either need a patch which will codify current order
of clone arguments (ie. ptid, ctid, tls; attached below - has the advantage
that clone2 stays with the same ABI as in 2.5.[56]x), or the arguments
of clone2 and clone should be reordered to match the IA-32 order
(which is ptid, tls, ctid).