openjdk8-fedora: fix the resulting module

Fixes https://github.com/cloudius-systems/osv/issues/508.

The root cause was that libjvm was assumed to be found in
/usr/lib/jvm/java/jre/lib/amd64. The module was missing an appropriate
symlink for /usr/lib/jvm/java.

I replicated changes made in modules/java/module.py

I also got rid of the GET script by moving logic to Makefile so that
incremental builds are faster (do not download RPMs every time).

Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>