Add a duk_trans_socket_active() function to allow application to allow for graceful shutdown

examples/debug-trans-socket/duk_trans_socket.h

@@ -16,6 +16,8 @@ duk_size_t duk_trans_socket_peek_cb(void *udata);
 void duk_trans_socket_read_flush_cb(void *udata);
 void duk_trans_socket_write_flush_cb(void *udata);
 
+duk_bool_t duk_trans_socket_active(void);
+
 #if defined(__cplusplus)
 }
 #endif  /* end 'extern "C"' wrapper */

examples/debug-trans-socket/duk_trans_socket_unix.c

@@ -89,6 +89,11 @@ void duk_trans_socket_finish(void) {
 	}
 }
 
+duk_bool_t duk_trans_socket_active(void)
+{
+	return server_sock >= 0;
+}
+
 void duk_trans_socket_waitconn(void) {
 	struct sockaddr_in addr;
 	socklen_t sz;

examples/debug-trans-socket/duk_trans_socket_windows.c

@@ -167,6 +167,11 @@ void duk_trans_socket_finish(void) {
 	}
 }
 
+duk_bool_t duk_trans_socket_active(void)
+{
+	return server_sock != INVALID_SOCKET;
+}
+
 void duk_trans_socket_waitconn(void) {
 	if (server_sock == INVALID_SOCKET) {
 		fprintf(stderr, "%s: no server socket, skip waiting for connection\n",