add stub for testing updates to scoped_timer

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/test/CMakeLists.txt

@@ -101,6 +101,7 @@ add_executable(test-z3
   sat_local_search.cpp
   sat_lookahead.cpp
   sat_user_scope.cpp
+  scoped_timer.cpp
   simple_parser.cpp
   simplex.cpp
   simplifier.cpp