Cant' build on FreeBSD

[mateuszkwiatkowski]

Hello,

I'm trying to build nerdctl on FreeBSD and I see this error:

package github.com/containerd/nerdctl
	imports github.com/containerd/containerd/pkg/cap: build constraints exclude all Go files in /home/kwiat/go/pkg/mod/github.com/containerd/containerd@v1.5.0-beta.4/pkg/cap
*** Error code 1

Containerd from tag v1.5.0-beta.4 builds fine:

$ ./bin/containerd -v
containerd github.com/containerd/containerd v1.5.0-beta.4 f201b78b9065f167071bf472a9708b3921c3d5d1

[AkihiroSuda]

Unsupported currently. Contribution is wanted.