eth/tracers: add basic native loader

eth/tracers/native/native.go

@@ -0,0 +1,18 @@
+package native
+
+import "github.com/ethereum/go-ethereum/core/vm"
+
+type Constructor func() vm.Tracer
+
+var tracers map[string]Constructor = make(map[string]Constructor)
+
+func Register(name string, fn Constructor) {
+	tracers[name] = fn
+}
+
+func New(name string) (vm.Tracer, bool) {
+	if fn, ok := tracers[name]; ok {
+		return fn(), true
+	}
+	return nil, false
+}