[Swan-dev] pluto: ikev2_create_child_sa.c: avoid NULL dereferences

[D. Hugh Redelmeier]

In process_v2_CREATE_CHILD_SA_request_continue_2, if ike is NULL:

- the comment I added says that the result is failure

- but the result returned is STF_OK (most analogous cases return 
  STF_INTERNAL_ERROR)

One of these is wrong and should be fixed.

A comment doesn't affect correctness (the part I added).

Is the STF_OK correct?  If so, we need to replace the incorrect
comment with a better description of what's up.

If the STF_OK is incorrect, what should the code do?

If the case is actually impossible, I suggest a passert.  That would 
simplify the code.