steamvr_lh: add frame mutex to prevent double free

src/xrt/drivers/steamvr_lh/device.cpp

@@ -372,6 +372,7 @@ ControllerDevice::set_haptic_handle(vr::VRInputComponentHandle_t handle)
 void
 Device::update_inputs()
 {
+	std::lock_guard<std::mutex> lock(frame_mutex);
 	ctx->maybe_run_frame(++current_frame);
 }
 

src/xrt/drivers/steamvr_lh/device.hpp

@@ -87,6 +87,8 @@ private:
 	std::vector<xrt_binding_profile> binding_profiles_vec;
 	uint64_t current_frame{0};
 
+	std::mutex frame_mutex;
+
 	void
 	init_chaperone(const std::string &steam_install);
 };