Mac OSX std.datetime / Posix daylight variable

[Jonathan M Davis]

Posix defines the tzset function along with a few helper items. From the Linux 
man page:

extern int daylight; 
extern long timezone; 
extern char *tzname[2]; 
void tzset(void); 

It seems that while these _are_ Posix, not all Posix systems declare all of them 
(which baffles me, but that's the way it goes it seems). tzset seem pretty 
universal, and I believe that tzname is essentially universal, but I'm not so 
sure about the others.

Currently, std.datetime uses tzset, tzname, and daylight on all Posix systems. 
It appears that for some reason, daylight is not declared on FreeBSD ( 
http://d.puremagic.com/issues/show_bug.cgi?id=5616 ). What I want to confirm is 
that this is _not_ a problem on Mac OS X.

As I understand it, std.datetime has been working just fine on Mac OS X, which 
would indicate that daylight _is_ declared on Mac OS X. Can anyone confirm this? 
If it is indeed the case, I'd like to have daylight added to druntime (where it 
belongs) for OSX. But if it's not actually on OSX, then we definitely don't want 
to declare it there.

- Jonathan M Davis