[hal] Implement stub mockdata on RoboRIO (#2575)

This makes it much more user-friendly to use simulation classes without needing
to ifdef for C++ to avoid linker errors or be very careful about construction
to avoid runtime errors in Java.

hal/src/main/native/athena/mockdata/MockHooks.cpp

@@ -0,0 +1,34 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/MockHooks.h"
+
+extern "C" {
+
+void HALSIM_SetRuntimeType(HAL_RuntimeType type) {}
+
+void HALSIM_WaitForProgramStart(void) {}
+
+void HALSIM_SetProgramStarted(void) {}
+
+HAL_Bool HALSIM_GetProgramStarted(void) { return false; }
+
+void HALSIM_RestartTiming(void) {}
+
+void HALSIM_PauseTiming(void) {}
+
+void HALSIM_ResumeTiming(void) {}
+
+HAL_Bool HALSIM_IsTimingPaused(void) { return false; }
+
+void HALSIM_StepTiming(uint64_t delta) {}
+
+void HALSIM_SetSendError(HALSIM_SendErrorHandler handler) {}
+
+void HALSIM_SetSendConsoleLine(HALSIM_SendConsoleLineHandler handler) {}
+
+}  // extern "C"