[CMake] cleaning targets

[Eric (Brad) Lemings]

Alexander Neundorf wrote:
> What would be the purpose of this ?
> What is the purpose of distclean anyway ?
>   
These are conventional GNU cleaning targets that apply to virtually all
software that is built from source.
The various cleaning targets are specified here:
http://www.gnu.org/software/automake/manual/html_node/Clean.html
The exact names of the targets are not so important as what they do (or
supposed to do).

Eric.