MPTCP tree in `linux-next`

[matttbe]

This is linked to this discussion.

It would be good to have MPTCP tree in linux-next, mainly for three reasons:

• to have our fixes there quicker, especially the ones addressing issues reported by automated tools like syzkaller, build warnings, etc.
• have our patches tested before being in net-next
• people expect all patches applied somewhere to be in linux-next

We can start simple:

• have our fixes from export-net in pending-fixes, on top of net. So taking commits between DO-NOT-MERGE: git markup: fixes other trees and DO-NOT-MERGE: git markup: fixes net.
• have our new features from the export branch in for-next. So taking commits between DO-NOT-MERGE: git markup: fixes net-next and DO-NOT-MERGE: git markup: features net-next.

If there are conflicts to cherry-pick new features because it depends on fixes in pending-fixes, these commits should be skipped. Maybe safer (and enough) to stop after the first cherry-pick issue.

The CI should also at least build pending-fixes (and for-next).

Note that patches sent to Netdev should be in a PR to avoid having different SHA for the same commit. So b4 should no longer be used to send those.

[matttbe]

Suggestion from Mat: having the for-next branch also containing the fixes, but then in linux-next, they shouldn't include pending-fixes.

(Or have a 3rd branch for-next-with-fixes)