[CMake] Operating system decisions

[ML]

Tyler,

>> Something like:
>>
>> if (OSX)
>>
>> if (Win32)
>>
>> if(Linux)
>
> http://www.cmake.org/Wiki/CMake_Useful_Variables/Logging_Useful_Variables
>
> Btw, we're switching to using an extra variable WINDOWS that we define
> as having the same value as WIN32. We got a lot of questions from
> developers wondering if WIN32 meant just 32-bit Windows. (We have a
> different way of determining whether a platform is 32-bit windows or
> 64-bit windows).

Thanks Tyler, is this avail in 2.6 (WINDOWS rather than using WIN32)  
or in a future release?

-Jason