Merge branch 'net-fix-the-features-flag-in-sctp_gso_segment'

Xin Long says:

====================
net: fix the features flag in sctp_gso_segment

Patch 1/2 is to improve the code in skb_segment(), and it is needed
by Patch 2/2.
====================

Link: https://lore.kernel.org/r/cover.1610703289.git.lucien.xin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>