[RFC] X server 21.1 release schedule

According to my recent testing the master branch is in relatively good shape. There exist known bugs, but we can start planning the release anyway.

I would like to propose release schedule for Xserver 21.1.

• 2021-08-16 - Driver ABI freeze
• 2021-08-30 - 21.1 RC 1
• every 2 weeks after that: a new RC until the final release

Note that there are no open MRs that affect the driver ABI and which make sense to merge at this time relatively near the RC phase. Thus for practical purposes the ABI freeze could as well be today.

Differently than previous releases of the X server, the server-21.1-branch release branch will branch off just before the RC 1 release and not after the final release of 21.1. This is because we want to remove the code of xwayland DDX as it is released separately.