[bugfix,release] Fix bug in graphtest.cc

In commit 3e405a0b a parameter 'eps'
was introduced for testAggregate(). However this parameter is not
supplied in the call (breaking the test) and it is never used
in the method.

dune/istl/paamg/test/graphtest.cc

@@ -498,7 +498,7 @@ void testGraph ()
 }
 
 
-void testAggregate(double eps)
+void testAggregate()
 {
 
   typedef Dune::FieldMatrix<double,1,1> ScalarDouble;