zephyr: Implement Alloc_With_System_Allocator (#3179)

Add zephyr libc malloc/realloc/free which were introduced since version 1.13.0.

core/shared/platform/zephyr/zephyr_platform.c

@@ -72,18 +72,20 @@ bh_platform_destroy()
 void *
 os_malloc(unsigned size)
 {
-    return NULL;
+    return malloc(size);
 }
 
 void *
 os_realloc(void *ptr, unsigned size)
 {
-    return NULL;
+    return realloc(ptr, size);
 }
 
 void
 os_free(void *ptr)
-{}
+{
+    free(ptr);
+}
 
 int
 os_dumps_proc_mem_info(char *out, unsigned int size)

product-mini/platforms/zephyr/simple/src/main.c

@@ -129,8 +129,12 @@ iwasm_main(void *arg1, void *arg2, void *arg3)
     init_args.mem_alloc_type = Alloc_With_Pool;
     init_args.mem_alloc_option.pool.heap_buf = global_heap_buf;
     init_args.mem_alloc_option.pool.heap_size = sizeof(global_heap_buf);
+#elif (defined(CONFIG_COMMON_LIBC_MALLOC)            \
+       && CONFIG_COMMON_LIBC_MALLOC_ARENA_SIZE != 0) \
+    || defined(CONFIG_NEWLIB_LIBC)
+    init_args.mem_alloc_type = Alloc_With_System_Allocator;
 #else
-#error Another memory allocation scheme than global heap pool is not implemented yet for Zephyr.
+#error "memory allocation scheme is not defined."
 #endif
 
     /* initialize runtime environment */