[PATCH] build: announce requirement for C11

[Morten Brørup]

> From: Bruce Richardson [mailto:bruce.richardson at intel.com]
> Sent: Wednesday, 3 May 2023 17.14
> 
> Add a deprecation notice informing users that we will require a C11
> compiler from 23.11 release onwards. This requirement was agreed by
> technical board to enable use of newer C language features, e.g.
> standard atomics. [1]
> 
> [1]
> http://inbox.dpdk.org/dev/DBAPR08MB58148CEC3E1454E8848A938998AB9@DBAPR08
> MB5814.eurprd08.prod.outlook.com/
> 
> Signed-off-by: Bruce Richardson <bruce.richardson at intel.com>

Acked-by: Morten Brørup <mb at smartsharesystems.com>