Fix duplicate symbols in plugin DLL.

PiperOrigin-RevId: 491340247
Change-Id: If559d60371ad604b94b92efd01ed6de9ecf6f2b0

plugin/elasticity/elasticity.cc

@@ -0,0 +1,26 @@
+// Copyright 2022 DeepMind Technologies Limited
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <mujoco/mjplugin.h>
+#include "cable.h"
+#include "solid.h"
+
+namespace mujoco::plugin::elasticity {
+
+mjPLUGIN_DYNAMIC_LIBRARY_INIT {
+  Cable::RegisterPlugin();
+  Solid::RegisterPlugin();
+}
+
+}  // namespace mujoco::plugin::elasticity