scanner: don't bug on too large values

scanner: don't bug on too large values

Add a new ERROR symbol to handle scanning of too large values.

 <cmdline>:1:36-99: Error: bad value '0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa'
 add rule ip test-ip4 input ct mark 0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
instead of:

 BUG: nft: scanner.l:470: nft_lex: Assertion `0' failed.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>