runtime: call initRand() before initHeap() during initialization.

The reason is that allocating without a heap is usually more visible
than using an uninitialized random generator which is subtle and may
lead to security vulnerabilities.

Based on suggestion from @eliasnaur

Signed-off-by: deadprogram <ron@hybridgroup.com>

src/runtime/scheduler_cooperative.go

@@ -243,8 +243,8 @@ func sleep(duration int64) {
 // run is called by the program entry point to execute the go program.
 // With a scheduler, init and the main function are invoked in a goroutine before starting the scheduler.
 func run() {
-	initHeap()
 	initRand()
+	initHeap()
 	go func() {
 		initAll()
 		callMain()