Fix for broken deleteActionHandler in shadow API

[johnhopwood]

The deleteActionHandler mechanism does not invoke the callback when shadows are deleted. To fix, make the deleteAcceptedTopic buffer static in aws_iot_shadow.c:

static char deleteAcceptedTopic[MAX_SHADOW_TOPIC_LENGTH_BYTES];

Currently, the handler is not found by _aws_iot_mqtt_internal_deliver_message b/c the topic was created on the stack.

https://github.com/aws/aws-iot-device-sdk-embedded-C/blob/master/src/aws_iot_shadow.c#L92

[chaurah]

Hi @johnhopwood,
Thank you for pointing this out. I have added a bugfix to our list of tasks for the next SDK release. I will update this issue and close when the release is out.
Please do let us know if you find any more issues with the SDK or have any further suggestions. Thank you for using AWS IoT.

Rahul