[wpilibj] Call abort() on Rio on caught Java exception (#6420)

On Rio, we simply want to restart the robot program as quickly as possible,
and don't want to risk a hang somewhere that will keep that from happening.

The main downside of this is it won't wait for threads to finish (e.g. data logs won't get a final flush).

hal/src/main/java/edu/wpi/first/hal/HAL.java

@@ -75,6 +75,9 @@ public final class HAL extends JNIWrapper {
    */
   public static native void exitMain();
 
+  /** Terminates the executable (at the native level). Does nothing in simulation. */
+  public static native void terminate();
+
   private static native void simPeriodicBeforeNative();
 
   private static final List<Runnable> s_simPeriodicBefore = new ArrayList<>();

hal/src/main/native/cpp/jni/HAL.cpp

@@ -7,6 +7,7 @@
 #include <jni.h>
 
 #include <cassert>
+#include <cstdlib>
 #include <cstring>
 
 #include <fmt/format.h>
@@ -82,6 +83,20 @@ Java_edu_wpi_first_hal_HAL_exitMain
   HAL_ExitMain();
 }
 
+/*
+ * Class:     edu_wpi_first_hal_HAL
+ * Method:    terminate
+ * Signature: ()V
+ */
+JNIEXPORT void JNICALL
+Java_edu_wpi_first_hal_HAL_terminate
+  (JNIEnv*, jclass)
+{
+#ifdef __FRC_ROBORIO__
+  std::abort();
+#endif
+}
+
 /*
  * Class:     edu_wpi_first_hal_HAL
  * Method:    simPeriodicBeforeNative

wpilibj/src/main/java/edu/wpi/first/wpilibj/RobotBase.java

@@ -453,6 +453,11 @@ public static <T extends RobotBase> void startRobot(Supplier<T> robotSupplier) {
       runRobot(robotSupplier);
     }
 
+    // On RIO, this will just terminate rather than shutting down cleanly (it's a no-op in sim).
+    // It's not worth the risk of hanging on shutdown when we want the code to restart as quickly
+    // as possible.
+    HAL.terminate();
+
     HAL.shutdown();
 
     System.exit(0);