[CMake] Enable warnings

[David Sveningsson]

Hi, I'm quite new with cmake and I can't figure out how to enable 
warnings for the generated makefiles/projects. For instance, I would 
like to use the -Wall flag with gcc.

-- 


//*David Sveningsson [eXt]*

Freelance coder | Game Development Student
http://sidvind.com

Thou shalt make thy program's purpose and structure clear to thy fellow 
man by using the One True Brace Style, even if thou likest it not, for 
thy creativity is better used in solving problems than in creating 
beautiful new impediments to understanding.