Immediately print internal exceptions in a non-main thread, in case they would cause a deadlock

(cherry picked from commit f1a6367)

Author: eregon

src/main/java/org/truffleruby/core/thread/ThreadManager.java

@@ -315,6 +315,8 @@ private void threadMain(RubyThread thread, Node currentNode, Supplier<Object> ta
             final String message = StringUtils
                     .format("%s terminated with internal error:", Thread.currentThread().getName());
             final RuntimeException runtimeException = new RuntimeException(message, e);
+            // Immediately print internal exceptions, in case they would cause a deadlock
+            runtimeException.printStackTrace();
             rethrowOnMainThread(currentNode, runtimeException);
             setThreadValue(context, thread, Nil.INSTANCE);
         } finally {