[CMake] cmake and MINGW's ld.exe issue

[D. Eimers]

> >"c:\mingw\bin\..\lib\gcc\mingw32\3.4.2\..\..\..\..\mingw32\bin\ld.exe:
> > cannot find -lgtkmm-2.4.lib "
> This looks like a bug in your CMakeList file.  When referring to a library,
> you should either have the full path to the library: /path/to/libgtkmn-2.4,
> or just gtkmn-2.4.  CMake will add the .lib when needed (when using visual
> studio compilers)
> 
> How are you specifying gtkmn-2.4 in your CMakeList file?

Yes, I am not adding the .lib part manually.