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_cores.go

@@ -135,8 +135,8 @@ func sleep(duration int64) {
 // This function is called on the first core in the system. It will wake up the
 // other cores when ready.
 func run() {
-	initHeap()
 	initRand()
+	initHeap()
 
 	go func() {
 		// Package initializers are currently run single-threaded.