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/runtime_wasmentry.go

@@ -34,8 +34,8 @@ func wasmEntryReactor() {
 	// Initialize the heap.
 	heapStart = uintptr(unsafe.Pointer(&heapStartSymbol))
 	heapEnd = uintptr(wasm_memory_size(0) * wasmPageSize)
-	initHeap()
 	initRand()
+	initHeap()
 
 	if hasScheduler {
 		// A package initializer might do funky stuff like start a goroutine and