Fix #430: disable rewriting of concatentations with constants because it breaks equality propagation

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

src/tactic/core/solve_eqs_tactic.cpp

@@ -111,6 +111,7 @@ class solve_eqs_tactic : public tactic {
                 if (m_produce_proofs) {
                     pr = m().mk_commutativity(m().mk_eq(lhs, rhs));
                 }
+                return true;
             }
             return false;
         }