Show correct line numbers in restore output for parser errors

Show correct line numbers in restore output for parser errors

Parser errors are reported by a wrong lineno at restore, bug reported
by Holger Eitzenberger:

  create foo6 hash:ip hashsize 64 family inet6
  add foo6 20a1:1234:5678::/64
  add foo6 20a1:1234:5679::/64

you get:

  ipset v5.2: Error in line 1: Syntax error: plain IP address must be supplied: 20a1:1234:5678::/64

Should be line 2 though.

The solution is to set the session lineno before parsing.