Add unit test suites (#3490)

tests/unit/wasm-vm/wasm-apps/app3/main.c

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2019 Intel Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <memory.h>
+#include <string.h>
+
+void
+on_init()
+{}
+
+int
+my_sqrt(int x, int y)
+{
+    return x * x + y * y;
+}
+
+void *
+null_pointer()
+{
+    void *ptr = NULL;
+    return ptr;
+}
+
+void *
+my_malloc(int size)
+{
+    return malloc(size);
+}