Change condition under which stage 2 is done.

It only makes sense to try to optimize the distribution of lift gas if
the amount of lift gas is constrained either by the maximum allowed
gaslift or total gas or the group is under individual control.

tests/test_glift1.cpp

@@ -181,6 +181,7 @@ BOOST_AUTO_TEST_CASE(G1)
         well_model.phaseUsage(),
         deferred_logger,
         well_state,
+        group_state,
         comm,
         /*glift_debug=*/false
     };