[PATCH?] vm/vm_map.h C++ incompatible

[Don Lewis]

On 25 Sep, Adriaan de Groot wrote:
> On 4.9-pre, vm/vm_map.h is not C++ compatible, due to this kind of call:
> 
> 	lockmgr(&(map)->lock, LK_RELEASE, (void *)0, curproc);
> 
> C++ (or rather, gcc 2.95.4) refuses to cast (void *) to the desired (struct 
> simplelock *), so C++ compilations that accidentally include vm/vm_map.h 
> fail. So do C++ compiles that intentionally pick it up, like kfontinst, which 
> is why I'm cc-ing kde at .
> 
> The attached patch replaces all the (void *) casts with casts to the correct 
> type; this fixes kfontinst, at the very least. It doesn't seem to hurt C 
> compilation, either.

Why not just use NULL instead of messing around with casts?