libio backward compat bug? involving setmntent()

[H.J. Lu]

> 
> 
> The appended slightly-out-of-spec code segfaults when compiled on a
> libc 2.0 system and run on a libc 2.1 system.  The problem is that
> setmntent() returns a new FILE*, but fclose is bound to the old
> fclose.
> 
> Do we want to support this, and if so, how?  (Have old fclose
> recognize when it's handed a new FILE* and call _IO_new_fclose?)
> 

Thanks for the bug report. I will fix it.


H.J.