[#216] netmap: Add policy decode fuzz test

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

netmap/policy_fuzz.go

@@ -0,0 +1,14 @@
+//go:build gofuzz
+// +build gofuzz
+
+package netmap
+
+func DoFuzzPlacementPolicyDecode(data []byte) int {
+	p := string(data)
+	if p == "" {
+		return 0
+	}
+	var pp PlacementPolicy
+	_ = pp.DecodeString(p)
+	return 1
+}