Pull up following revision(s) (requested by maxv in ticket #665):

sys/netinet6/icmp6.c: revision 1.215

Style, and four fixes:

* Remove the (disabled) IPPROTO_ESP check. If the packet was decrypted it
  will have M_DECRYPTED, and this is already checked.
* Memory leaks in icmp6_error2. They seem hardly triggerable.
* Fix miscomputation in _icmp6_input, the ICMP6 header is not guaranteed
  to be located right after the IP6 header. ok mlelstv@
* Memory leak in _icmp6_input. This one seems to be impossible to trigger.

(martin)