nokia.image-processing tests

This list is starting to get unwieldy, which will make conflict resolution with other changes to it (like in #537) difficult. Can you replace it with a variable? Something like:

```
PACKAGE_FILES = \
  tests.jar \
  gnu/testlet/vm/test.png \
  gfx/images/* \
  midlets/test.png \
  midlets/favouriteartists/images/* \
  midlets/blogwriter/images/* \
  midlets/rlinks/images/* \
  com/sun/cldc/io/utf8.txt \
  org/mozilla/io/test.jpg \
  $(NULL)

tests.jar: $(SRCS) Testlets.java
…
	jar uvf $(PACKAGE_FILES) > /dev/null
```