Minor issue: rdkafka_consumer_example_cpp segfault

[ciasom]

Description

When running rdkafka_consumer_example_cpp with option -X dump, it got segfault when trying to dump topic configurations since the pointer of the topic Conf object has been deleted before dumping.

How to reproduce

Run something like:
./examples/rdkafka_consumer_example_cpp -g MyGroup -X dump MyTopic

Checklist

Please provide the following information:

• librdkafka version (release number or git tag): master branch
• Apache Kafka version: 0.10.0.1
• librdkafka client configuration:
• Operating system:
  Linux 3.13.0-98-generic dead-lock in multi-thread enviroment #145-Ubuntu SMP Sat Oct 8 20:13:07 UTC 2016 x86_64 GNU/Linux
• Using the legacy Consumer
• Using the high-level KafkaConsumer
• Provide logs (with debug=.. as necessary) from librdkafka
• Provide broker log excerpts
• Critical issue