PATCH: malloc.c cleanups

[Wolfram Gloger]

> > OK, I see.  It's probably a matter of taste, but I would prefer to see
> > sizeof(main_arena.av[0]) used rather than the cast NULL pointer.
> 
> Fine by me.
> 
> Will you approve the patch if next_bin and prev_bin are changed like so?
> 
> #define next_bin(b)    ((mbinptr)((char*)(b) + 2 * sizeof(main_arena.av[0])))
> #define prev_bin(b)    ((mbinptr)((char*)(b) - 2 * sizeof(main_arena.av[0])))

Sure, but Andreas "Mr Standard" Schwab has convinced me that your
initial version is fine also.

> BTW, who has approval authority for malloc.c changes?
> You only?  Uli only?  Both of you?

I'm not checking in changes, and I certainly won't veto changes.  I
just give my opinion.

Regards,
Wolfram.