Refine is_xip_file and pointer range check (#965)

Refine is_xip_file check, when e_type isn't E_TYPE_XIP, just return false
and no need to go through all the other sections of the AOT file.

Refine pointer range check, convert pointer to uintptr_t type before
comparison to yield possible sanitizer pointer overflow error.

core/iwasm/aot/aot_loader.c

@@ -90,7 +90,8 @@ static bool
 check_buf(const uint8 *buf, const uint8 *buf_end, uint32 length,
           char *error_buf, uint32 error_buf_size)
 {
-    if (buf + length < buf || buf + length > buf_end) {
+    if ((uintptr_t)buf + length < (uintptr_t)buf
+        || (uintptr_t)buf + length > (uintptr_t)buf_end) {
         set_error_buf(error_buf, error_buf_size, "unexpect end");
         return false;
     }