/*
* cpu_lwp_fork: finish a new LWP (l2) operation.
*
* First LWP (l1) is the process being forked. If it is &lwp0, then we
* are creating a kthread, where return path and argument are specified
* with `func' and `arg'.
*
* If an alternate user-level stack is requested (with non-zero values
* in both the stack and stacksize arguments), then set up the user stack
* pointer accordingly.
*/