[Cmake] CMake error output improvments

[Brad King]

> That seems all good ;-)
> Just make sure that the file/line err. number format match one standard
> that -for example-
> will permit perfect integration in development environments like Emacs, VC6
> It's just about how to dispose your error line file and line number info. so
> it give you the ability to double-click directly on the error and the file
> is opened in your GUI ...

This capability has been tested in emacs, and it works.

-Brad