lx_emul: import shadow sched.c from allwinner repo

Ref genodelabs/genode#4411

repos/dde_linux/src/lib/lx_emul/shadow/kernel/sched/sched.c

@@ -0,0 +1,23 @@
+/*
+ * \brief  Supplement for emulation of kernel/sched/core.c
+ * \author Norman Feske
+ * \date   2021-06-02
+ */
+
+/*
+ * Copyright (C) 2021 Genode Labs GmbH
+ *
+ * This file is distributed under the terms of the GNU General Public License
+ * version 2.
+ */
+
+#include <linux/sched.h>
+
+int __cond_resched(void)
+{
+	if (should_resched(0)) {
+		schedule();
+		return 1;
+	}
+	return 0;
+}