Merge branch 'ipv6-tcp-no-longer-rebuild-fl6-at-each-transmit'

Eric Dumazet says:

====================
ipv6: tcp: no longer rebuild fl6 at each transmit

TCP v6 spends a good amount of time rebuilding a fresh fl6 at each
transmit in inet6_csk_xmit()/inet6_csk_route_socket().

TCP v4 caches the information in inet->cork.fl.u.ip4 instead.

This series changes TCP v6 to behave the same, saving cpu cycles
and reducing cache line misses and stack use.
====================

Link: https://patch.msgid.link/20260206173426.1638518-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>