fix problem in CMake error message
fix problem in CMake error message

Remove unmatched '${' in error message. CMake itself might not have
minded, but it confuses the heck out of both katepart and vim syntax
highlighting.

rkhlebnikov/PythonQt,msmolens/PythonQt,rkhlebnikov/PythonQt,msmolens/PythonQt,rkhlebnikov/PythonQt,rkhlebnikov/PythonQt,msmolens/PythonQt,msmolens/PythonQt