[Click] LookupIP6Route patch

[Roman Chertov]

Hello,
    The LookupIP6Route element's header file needs to be patched to 
declare the element of PUSH processing, as currently it is declared as 
AGNOSTIC.  The element can be currently installed in PULL processing, 
but it does nothing and simply passes packets from input[0] to 
output[0].  I think it is more correct to reject a PULL configuration 
because no IPv6 routing would be performed.

Roman