[CMake] Making CMakeLists.txt files work for 32 and 64-bit compiles

[gga]

New to cmake but so far I love it. 

First question I have is whether CMake is 32-bits/64-bits aware and
whether there is a way to set up a project to compile as either native
only, 32-bits only, 64-bits only or both.
So far I am unable to find anything of that nature in its built-in
configuration files or on-line documentation. 
I can obviously pass the CPP/LD switches myself, as a work-around,
albeit that kind of beats the point, as I am not fully aware of all the
appropriate switches in each platform.

I'm thinking something along the lines of -DCMAKE_BUILD_TYPE=Release,
like -DCMAKE_BUILD_ARCH=64.

-- 
Gonzalo Garramuño
ggarra at advancedsl.com.ar

AMD4400 - ASUS48N-E
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