re PR libgcj/1758 (java.util package lacks TreeMap)

re PR libgcj/1758 (java.util package lacks TreeMap)

        * java/util/TreeMap.java: New file.
        * java/util/TreeSet.java: New file.
        * Makefile.am: Add TreeMap and TreeSet. Enable WeakHashMap.
        * Makefile.in: Rebuilt.
        * java/util/HashSet.java (clone): Use constructor instead of calling
        clone on itself.
        * java/util/SortedSet.java: Sync with classpath.
        * java/util/HashMap.java (hash): Use if statement instead of ternary,
        for clarity.
	Resolves PR libgcj/1758.
	Resolves PR java/1684.

From-SVN: r39657