make libnetwork compile on freebsd (again)

Signed-off-by: Alexey Guskov <lexag@mail.ru>

libnetwork/sandbox/interface_freebsd.go

@@ -0,0 +1,4 @@
+package sandbox
+
+// IfaceOption is a function option type to set interface options
+type IfaceOption func()

libnetwork/sandbox/namespace_unsupported.go

@@ -1,4 +1,4 @@
-// +build !linux,!windows
+// +build !linux,!windows,!freebsd
 
 package sandbox
 

libnetwork/sandbox/neigh_freebsd.go

@@ -0,0 +1,4 @@
+package sandbox
+
+// NeighOption is a function option type to set neighbor options
+type NeighOption func()

libnetwork/sandbox/sandbox_freebsd.go

@@ -0,0 +1,23 @@
+package sandbox
+
+// GenerateKey generates a sandbox key based on the passed
+// container id.
+func GenerateKey(containerID string) string {
+	maxLen := 12
+	if len(containerID) < maxLen {
+		maxLen = len(containerID)
+	}
+
+	return containerID[:maxLen]
+}
+
+// NewSandbox provides a new sandbox instance created in an os specific way
+// provided a key which uniquely identifies the sandbox
+func NewSandbox(key string, osCreate bool) (Sandbox, error) {
+	return nil, nil
+}
+
+// GC triggers garbage collection of namespace path right away
+// and waits for it.
+func GC() {
+}

libnetwork/sandbox/sandbox_unsupported.go

@@ -1,4 +1,4 @@
-// +build !linux,!windows
+// +build !linux,!windows,!freebsd
 
 package sandbox