Fix @see to external class in api to allow compilation with Java 8

The recently added GarbageCollectorListener came with a @see to a JGit
class. While Java 7 did not error out on that, Java 8 does:

  [...]/events/GarbageCollectorListener.java:34: error: reference not found
     * @see org.eclipse.jgit.api.GarbageCollectCommand#call()
            ^

As Java 8's javadoc currently (1.8.0_45) even complains when adding a
“-link”, we work around the issue by transforming the @see to the
classname into a @see with a full <a/>.

Change-Id: I1c061d5219b4fe8818d3fca8a56b4a433aa557d4
1 file changed