vm: close the console when exiting

This prevents an endless loop caused by the nvidia drivers on linux.
See http://www.nvnews.net/vbulletin/showthread.php?t=164619

vm/os-unix.cpp

@@ -496,6 +496,15 @@ void factor_vm::open_console()
 	pthread_mutex_init(&stdin_mutex, NULL);
 }
 
+// This method is used to kill the stdin_loop before exiting from factor.
+// A Nvidia driver bug on Linux is the reason this has to be done, see:
+// http://www.nvnews.net/vbulletin/showthread.php?t=164619
+void factor_vm::close_console()
+{
+	pthread_mutex_lock(&stdin_mutex);
+	pthread_kill(stdin_thread, SIGTERM);
+}
+
 void factor_vm::lock_console()
 {
 	// Lock the stdin_mutex and send the stdin_loop thread a signal to interrupt

vm/os-windows.cpp

@@ -317,6 +317,10 @@ void factor_vm::unlock_console()
 {
 }
 
+void factor_vm::close_console()
+{
+}
+
 void factor_vm::sampler_thread_loop()
 {
 	LARGE_INTEGER counter, new_counter, units_per_second;

vm/run.cpp

@@ -5,6 +5,7 @@ namespace factor
 
 void factor_vm::primitive_exit()
 {
+	close_console();
 	exit((int)to_fixnum(ctx->pop()));
 }
 

vm/vm.hpp

@@ -732,6 +732,7 @@ struct factor_vm
 	void start_sampling_profiler_timer();
 	void end_sampling_profiler_timer();
 	void open_console();
+	void close_console();
 	void lock_console();
 	void unlock_console();
 	static void abort();