[CMake] Recognizing GNU compiler doesn't work

[Alexander Neundorf]

On Friday 24 October 2008, Niko Vuokko wrote:
> Simply put variable CMAKE_COMPILER_IS_GNUC is an empty string and thus
> false.

It's "CMAKE_COMPILER_IS_GNUCC" 
(http://www.cmake.org/Wiki/CMake_Useful_Variables)

Alex