x/sys: FreeBSD 11 builders on release-branch.go1.17 broken since CL 415714

[bcmills]

CL 415714 regenerated x/sys with compatibility only for FreeBSD 12 and higher.

However, the FreeBSD 11_4 builders are still configured to run the repo on release-branch.go1.17, and are now failing on that branch.

We should either fix x/sys to restore compatibility until release-branch.go1.17 is no longer being maintained, or explicitly disable this repo on those builders.

(attn @golang/freebsd, @golang/release)

[paulzhol]

FreeBSD 11.4 is EOL since September 30, 2021. release-branch.go1.19 was already branched out. I wouldn't like to revert if 1.17 is about to be dropped.

[bcmills]

Sounds good. Want to send a CL to disable those builders for the x/sys repo?

[bcmills]

The relevant changes would be here:
https://cs.opensource.google/go/x/build/+/master:dashboard/builders.go;l=1546-1550;drc=3b840f6e8cc9cc3f657fb9b11ad755f990f2efe2
https://cs.opensource.google/go/x/build/+/master:dashboard/builders.go;l=1605-1609;drc=3b840f6e8cc9cc3f657fb9b11ad755f990f2efe2

[gopherbot]

Change https://go.dev/cl/416894 mentions this issue: dashboard: drop host-freebsd-11_2, host-freebsd-11_4 builders