Fixes handling bitwise operators for z3 model checker

test/libsolidity/smtCheckerTests/operators/bitwise_operators_do_not_throw_exceptions.sol

@@ -0,0 +1,12 @@
+contract C {
+    // tests that bitwise operators are parsed from z3 answer
+    function test(uint x, uint y) public pure {
+        x | y;
+        x & y;
+        x ^ y;
+        assert(true);
+    }
+}
+// ====
+// SMTEngine: all
+// ----