test: changed the buffer offset

to avoid problem with the new behaviour of new V8 BackingStore API. By
changing the offset, the base address of each test case will be
different.

Fixes: nodejs#31061

test/addons/buffer-free-callback/test.js

@@ -16,20 +16,24 @@ function check(size, alignment, offset) {
   global.gc();
 }
 
+// NOTE: If adding more check() test cases,
+// be sure to not duplicate alignment/offset.
+// Refs: https://github.com/nodejs/node/issues/31061#issuecomment-568612283
+
 check(64, 1, 0);
 
 // Buffers can have weird sizes.
-check(97, 1, 0);
+check(97, 1, 1);
 
 // Buffers can be unaligned
 check(64, 8, 0);
 check(64, 16, 0);
 check(64, 8, 1);
 check(64, 16, 1);
-check(97, 8, 1);
-check(97, 16, 1);
 check(97, 8, 3);
 check(97, 16, 3);
+check(97, 8, 5);
+check(97, 16, 5);
 
 // Empty ArrayBuffer does not allocate data, worth checking
-check(0, 1, 0);
+check(0, 1, 2);