ctf: add implicitly defined enums at the end of the range

Make implicitly declared enumerations have a value == range.max + 1

To be clear:

enum bob {4-7};
enum alice;

bob is added with a range of 4-7
alice is now added with a range of 8-8 instead of 5-8 as it was before

Link: lttng/lttng-scope#79
Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Suggested-by: Jeremie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ic88b5749e1a19548f8c1342f54acf290a173a28d
Signed-off-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/131749
Tested-by: CI Bot
Reviewed-by: Patrick Tasse <patrick.tasse@gmail.com>
Tested-by: Patrick Tasse <patrick.tasse@gmail.com>

ctf/org.eclipse.tracecompass.ctf.core/src/org/eclipse/tracecompass/ctf/core/event/types/EnumDeclaration.java

@@ -238,7 +238,8 @@ public boolean add(long low, long high, @Nullable String label) {
      * @since 2.0
      */
     public boolean add(@Nullable String label) {
-        return add(fLastAdded.fFirst + 1, fLastAdded.fSecond + 1, label);
+        // add the item with a value of max(range)+1 for low and high to ensure no overlap
+        return add(fLastAdded.fSecond + 1, fLastAdded.fSecond + 1, label);
     }
 
     /**