* There's no OPENCV_BINARY_DIR variable;
* No need to append CMakeFiles/CMakeTmp, as CMake does it for you;
* Output variables are unused;
* Wrong usage of CMAKE_FLAGS;
* Small quoting and style issues.

Now the HAVE_* macros are set using cvconfig.h. Previously most
of them already were there, but were always undefined. One,
HAVE_COCOA, I had to add.

This also makes the CMake code more consistent; now, WITH_* variables
are always checked in cmake/*, while HAVE_* variables are checked in
modules/highgui/CMakeLists.txt.

I don't know why it didn't work for the original author, but it definitely
works now.

Also, removing explicit include path configuration,
since QT_USE_FILE takes care of that.

Issue #2868