Previously, run.py would assume that the opencv_java library is in the
same directory as the tests, which is only true on Windows.

The library path depends on the build configuration, which may not be
known until the actual build (e.g. with the Visual Studio generators),
so it can't be stored in the CMake cache for run.py to read. I didn't
want to hardcode into run.py where the library is on each platform,
either. So that's why I used the current scheme with the properties
file. It also makes running the tests without run.py a little easier.

We don't use it, anyway.

Java inlines static finals if they're defined with a constant expression. In
case of version constants we don't want that to happen, since they obviously
change from version to version. If the user substitutes a different OpenCV
jar without recompiling, we want user code to still have relevant values for
the version constants.

This arranges that by turning constant values into function calls, which no
longer count as a constant expression.

Because apparently I love running performance tests for debug builds.

Signed-off-by: Han Qiang <a0byte@gmail.com>