initialize WASI stdio handles to invalid for better error handling (#4092)

* initialize WASI stdio handles to invalid for better error handling
* implement os_invalid_raw_handle function for consistent invalid handle representation

core/shared/platform/alios/alios_platform.c

@@ -79,3 +79,9 @@ os_dcache_flush()
 void
 os_icache_flush(void *start, size_t len)
 {}
+
+os_raw_file_handle
+os_invalid_raw_handle(void)
+{
+    return -1;
+}