Work around Windows test failure

I am uncertain why this works, but it does. Previously, `rtti_test` was
failing due to non-zero data appearing in the `l_buggy` `Buggy_Struct`.

The issue was caused by calling `runtime.default_random_generator` with
a pointer to the state, somehow. The pointer could be on the stack or in
the heap; it did not matter.

I found two workarounds.

- One is to move the RNG setup behind the call to `free_all`.
- The other is to construct the random generator manually.

Despite my digging and testing, I could find no reason as to why this
works or what the fundamental issue was to begin with. If anyone comes
upon this in the future with direct access to a Windows machine, I
recommend stepping through the program with a debugger to investigate
more deeply into why this happens.

core/testing/runner.odin

@@ -107,10 +107,14 @@ run_test_task :: proc(task: thread.Task) {
 		options = Default_Test_Logger_Opts,
 	}
 
-	free_all(context.temp_allocator)
+	random_generator_state: runtime.Default_Random_State
+	context.random_generator = {
+		procedure = runtime.default_random_generator_proc,
+		data = &random_generator_state,
+	}
+	rand.reset(data.t.seed)
 
-	random_generator_state := rand.create(data.t.seed)
-	context.random_generator = rand.default_random_generator(&random_generator_state)
+	free_all(context.temp_allocator)
 
 	data.it.p(&data.t)