Delete obsolete JarLinkUtil

Since we are now using the maven-shade-plugin to flatten out our
dependencies into a single stand-alone JAR we no longer need to
use our own command line utility.

Change-Id: I057c782cc66c44f11ed2ff2b4b4ca9cc82c7426a
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>