Update kernels to 4.14.169 or later

[emkll]

Description

Updating will provide improve cache handling to mitigate CVE-2020-0549 (https://cacheoutattack.com/)
A microcode update will be provided by Intel at a later date.

In order to exploit this vulnerability, an attacker requires:

1. Local code execution on the server
2. A CPU that supports Intel TSX

We do disable TSX in the kernel config: https://github.com/freedomofpress/ansible-role-grsecurity-build/blob/master/files/config-securedrop-4.14#L626 , so this vulnerability may not even be exploitable by an attacker.

Since the likelihood of exploitation is extremely unlikely. I propose we update Kernels as part of the 1.3.0 release.

[conorsch]

Opened a dependency PR in the build repo: freedomofpress/ansible-role-grsecurity-build#57

Will kick off a server-kernel build with those new deps.