(detected by enabling additional checkstyle modules)

This commit also removes unnecessary uses of the "private" modifier in
the Java tests/examples.  The default access modifier disallows access
outside of the package, and none of these classes is in a package.  The
only reason we use "private" with member variables in these classes is
to make checkstyle happy, because we want it to enforce that behavior in
the TurboJPEG API code.