Fix conversion of owning pointer to non-owning in C++98

Should fix the build failure of test RepeatUntilCalcArrayType in
`cpp_stl_98`, which looks like this
(https://github.com/kaitai-io/ci_artifacts/blob/7b931f2439b708823fd25a1ee08c7e582b70e261/test_out/cpp_stl_98/build-1.log#L1898-L1901):

```
/tests/compiled/cpp_stl_98/repeat_until_calc_array_type.cpp: In member function 'repeat_until_calc_array_type_t::record_t* repeat_until_calc_array_type_t::first_rec()':
/tests/compiled/cpp_stl_98/repeat_until_calc_array_type.cpp:98:44: error: request for member 'get' in '((repeat_until_calc_array_type_t*)this)->repeat_until_calc_array_type_t::recs_accessor()->std::vector<repeat_until_calc_array_type_t::record_t*>::front()', which is of pointer type 'repeat_until_calc_array_type_t::record_t*' (maybe you meant to use '->' ?)
   98 |     m_first_rec = recs_accessor()->front().get();
      |                                            ^~~
```

shared/src/main/scala/io/kaitai/struct/languages/CppCompiler.scala

@@ -866,7 +866,17 @@ class CppCompiler(
       case ct: ComplexDataType => ct.isOwningInExpr
       case _ => false
     }
-    handleAssignmentSimple(instName, if (isOwningInExpr) s"$valExpr.get()" else valExpr)
+    val valExprConverted = if (isOwningInExpr) {
+      config.cppConfig.pointers match {
+        case RawPointers =>
+          valExpr
+        case UniqueAndRawPointers =>
+          s"$valExpr.get()"
+      }
+    } else {
+      valExpr
+    }
+    handleAssignmentSimple(instName, valExprConverted)
   }
 
   override def enumDeclaration(curClass: List[String], enumName: String, enumColl: Seq[(Long, EnumValueSpec)]): Unit = {