missing: move rand related definitions to missing_random.h

src/basic/missing_random.h

@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+#pragma once
+
+#if USE_SYS_RANDOM_H
+#  include <sys/random.h>
+#else
+#  include <linux/random.h>
+#endif
+
+#ifndef GRND_NONBLOCK
+#define GRND_NONBLOCK 0x0001
+#endif
+
+#ifndef GRND_RANDOM
+#define GRND_RANDOM 0x0002
+#endif