java_string_library_preprocesst isn't a messaget

Pass a message handler as an argument to several of its functions, but do not
construct a messaget object without a configured message handler as that is
deprecated.

Author: tautschnig

jbmc/src/java_bytecode/java_bytecode_language.cpp

@@ -1514,8 +1514,8 @@ bool java_bytecode_languaget::convert_single_method_code(
         writable_symbol, cmb->get().method.local_variable_table, symbol_table);
     }
     // Populate body of the function with code generated by string preprocess
-    codet generated_code =
-      string_preprocess.code_for_function(writable_symbol, symbol_table);
+    codet generated_code = string_preprocess.code_for_function(
+      writable_symbol, symbol_table, message_handler);
     // String solver can make calls to functions that haven't yet been seen.
     // Add these to the needed_lazy_methods collection
     notify_static_method_calls(generated_code, needed_lazy_methods);