[gentoo-java] Reminder about version bumps with new jars

[Petteri Räty]

Remember to check all reverse dependencies when version bumping if you
add a second jar to a package because stuff using ant properties with
java-pkg_getjars can break. This happens when the build.xml uses
location instead of path and as such does not tolerate many jars in the
value. This was insipired by jcommon-1.0.8 version bump breaking
jfreechart in ~arch.

Regards,
Petteri