Spec, libcni: add disableGC flag

[squeed]

This allows administrators to disable garbage collection in exceptional circumstances, such as multiple runtimes sharing a network configuration.

[coveralls]

coverage: 63.69% (+0.09%) from 63.596%
when pulling c283314 on squeed:gc-improvements
into cebd7df on containernetworking:main.

[s1061123]

Should we modify pkg/types/types.go to add disableGC here?

https://github.com/squeed/cni/blob/a2d52a4f952c8f216b5bf8e8cc7542a8d275fd55/pkg/types/types.go#L117-L123

[henry118]

Should we modify pkg/types/types.go to add disableGC here?

https://github.com/squeed/cni/blob/a2d52a4f952c8f216b5bf8e8cc7542a8d275fd55/pkg/types/types.go#L117-L123

Same question. However I don't see any references of type NetConfList. Wonder if we can just remove that type?

[s1061123]

Should we modify pkg/types/types.go to add disableGC here?
https://github.com/squeed/cni/blob/a2d52a4f952c8f216b5bf8e8cc7542a8d275fd55/pkg/types/types.go#L117-L123

Same question. However I don't see any references of type NetConfList. Wonder if we can just remove that type?

This is not private scope, just public scope hence other repos use that, like https://github.com/k8snetworkplumbingwg/multus-cni/blob/75c02450209c749c67b571d1add5b0cf5b39d732/pkg/types/types.go#L101

So removing it causes lots of changes out side of this repo, under CNI plugins. So we should not do that.

[squeed]

@henry118 Agreed, NetConfList doesn't seem to be used internally, so adding DisableCheck and DisableGC to it was a bit odd. But better to be consistent.

[henry118]

LGTM

[s1061123]

Looks good to me.