MINOR: quic: remove ->offset qf_crypto struct field

MINOR: quic: remove ->offset qf_crypto struct field

This patch follows this previous bug fix:

    BUG/MINOR: quic: reorder fragmented RX CRYPTO frames by their offsets

where a ebtree node has been added to qf_crypto struct. It has the same
meaning and type as ->offset_node.key field with ->offset_node an eb64tree node.
This patch simply removes ->offset which is no more useful.

This patch should be easily backported as far as 2.6 as the one mentioned above
to ease any further backport to come.

(cherry picked from commit 31c17ad837195c70fb6d4e427845ded1c6acffaa)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 4a1a08be4f34feafb637115a1d8536ad70a2df33)
[cf: Some changes were made inlined in quic_tx.c because some functions does
 not exist in 3.2 and lower]
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 565d73a3b1d6fa562408392bb55340a5e7b8b967)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>