This patch is *not* changing the licensing terms of this library (which
was initially released under GPLv2 and later on extended to GPLv2+ after
contacting all the contributors who kindly agreed to extend it to any
later GPL version).

Jan says: "In libnetfilter_conntrack, there are many .c files declaring
GNU GPL incorporated herein by reference without telling which version(s)
exactly apply. Given src/main.c for example is actually GPL-2.0+,
the reference made is ambiguous."

This patch should definitely clarify this.

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