Java related changes in intrepid

Recently Openjdk6 was promoted to main; with today's upload of java-common,
OpenJDK6 is the default java runtime / development kit in main, on all
architectures.

 - On amd64, i386, lpia and sparc, the Hotspot VM, including the JIT compiler
   is used as the VM.

 - On ia64, the Hotspot VM, using the byte code interpreter is used.

 - On powerpc, the Cacao VM, including the Cacao JIT compiler is used as the
   VM.

What will change for the packaging?

 - Use of the default-jre-headless, default-jre, default-jdk,
   default-jdk-builddep packages is preferred in favour of a specific
   runtime/jdk. The packages provide a symlink /usr/lib/jvm/default-java
   to point to our preferred choice of jvm/sdk.

 - build dependencies: If a source package builds a "-gcj" package, don't
   stop building it yet. This will slow down the gij runtime. Instead,
   use "default-jdk-builddep", which depends on the default jdk and
   java-gcj-compat-dev. If no "-gcj" package is built, use default-jdk
   as a build dependency.

 - dependencies: For a dependency, which doesn't require an UI, use

       default-jre-headless | java2-runtime-headless

   for all other dependencies, use

       default-jre | java2-runtime

   Replace java2- with java5- only if newer language features are required.

For intrepid we strive to replace all direct references to java-gcj-compat-dev
and java-gcj-compat with references to default-*.

  Matthias