[Cooker] Java packages now built using icedtea by default

Java packages are now built using icedtea by default on ix86 and x86_64,
via new java-rpmbuild virtual jdk package.


According to my earlier post, the next planned java build changes are:

> - split eclipse-ecj out of eclipse (debian-style) to allow main/contrib split
> - move rest of eclipse to contrib
> - move most of java stack to contrib, leaving only jpackage-utils, java-rpmbuild, gcc4.3, java-1.5.0-gcj, java-1.7.0-icedtea, eclipse-ecj, and a handful of dependencies to main
>
> Possibly at some point later:
> - removal of gcj aot compiling


--
Anssi Hannula