gffi finalizer does not return correct value when used from destroy()

[GoogleCodeExporter]

finalizeWith should pass the return value back to destroy as though the C 
closure had been invoked directly.

spotted thusly:

const _close        = new dl.CFunction(ffi.int, "close",        ffi.int);

...
  this.fd   = +fd;
  this.gcFd = fd;       /* keep the boxed fd as a GC root to prevent finalization */
...

    if (this.gcFd.destroy() != 0)
      throw new Error("Could not close socket on fd " + (0+this.fd) + syserr());


The exception was thrown, however truss confirms that the system call returned 
zero.

Original issue reported on code.google.com by wes@page.ca on 11 Dec 2012 at 6:35