[rviz_rendering] check if OGRE_PLUGIN_DIR is still required

[wjwwood]

Since we're using static linking, rather than dynamically loading ogre plugins, we may no longer need to set it from the build system:

• rviz/rviz_rendering/CMakeLists.txt

  Line 86 in ca8f42e

  # TODO(wjwwood): this might not be required anymore with static linking

• https://github.com/ros2/rviz/blob/ros2/rviz_rendering/src/rviz_rendering/resource_config.cpp#L47

This is where we statically load and avoid needing to load dynamically:

• rviz/rviz_rendering/src/rviz_rendering/render_system.cpp

  Lines 183 to 184 in ca8f42e

  	render_system_gl_plugin_ = new Ogre::GLPlugin();
  	ogre_root_->installPlugin(render_system_gl_plugin_);

[Martin-Idel-SI]

We checked it by just deleting the lines and rebuilding everything. No errors and it runs on Linux at least, so it seems to be unnecessary now. What do you propose to do with it? Do you want a Pull-Request deleting this?

[wjwwood]

Do you want a Pull-Request deleting this?

👍 Yes, please.