rand: reorganize (step 1)

vlib/rand/system_rng.js.v

@@ -0,0 +1,15 @@
+// Copyright (c) 2019-2020 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+module rand
+
+// Until there's a portable, JS has a seeded way to produce random numbers
+// and not just Math.random(), use any of the existing implementations
+// as the System's RNG
+type SysRNG WyRandRNG
+
+// In the JS version, we simply return the same int as is normally generated.
+[inline]
+pub fn (r SysRNG) default_rand() int {
+	return r.int()
+}