[CMake] Differentiate between Linux and FreeBSD

[Pau Garcia i Quiles]

Quoting Horacio Sanson <hsanson at gmail.com>:

> I can use IF(WIN32) and IF(UNIX) to set some variables depending if
> cmake is executed in Windows or UNIX systems. The problem is that UNIX
> in this context includes both Linux and FreeBSD.
>
> Has CMake a way to know if it is running in a Linux box or a FreeBSD box??

Use the CMAKE_SYSTEM_NAME variable:
http://www.cmake.org/Wiki/CMake_Useful_Variables#System_.26_Compiler_Information

-- 
Pau Garcia i Quiles
http://www.elpauer.org
(Due to my workload, I may need 10 days to answer)