Add test for Java integers with --no-simplify

See issue cbmc#1015 for detail.

Author: smowton

regression/cbmc-java/integer_without_simplify1/test.class

@@ -0,0 +1,7 @@
+CORE
+test.class
+--no-simplify --function test.f --cover location
+^EXIT=0$
+^SIGNAL=0$
+--
+^warning: ignoring

regression/cbmc-java/integer_without_simplify1/test.desc

@@ -0,0 +1,10 @@
+
+public class test {
+
+  public void f() {
+
+    int x = 50;
+
+  }
+
+}

regression/cbmc-java/integer_without_simplify1/test.java

@@ -1417,11 +1417,10 @@ codet java_bytecode_convert_methodt::convert_instructions(
     else if(statement==patternt("?ipush"))
     {
       assert(results.size()==1);
-      namespacet ns(symbol_table);
-      // Force a simplify here in case we have --no-simplify
-      // because the simplifier is the only pass that knows how to
-      // deal with this cast from integer_typet:
-      results[0]=simplify_expr(typecast_exprt(arg0, java_int_type()), ns);
+      mp_integer int_value;
+      bool ret=to_integer(to_constant_expr(arg0), int_value);
+      INVARIANT(!ret, "?ipush argument should be an integer");
+      results[0]=from_integer(int_value, java_int_type());
     }
     else if(statement==patternt("if_?cmp??"))
     {