[collectd] should utils_llist duplicate and own char *key?

[Luke Heberling]

Florian Forster wrote:
> I don't fully understand what you mean by `lifetime', because if the key
> is freed from outside the AVL tree the code will access invalid memory
> and fial horribly at best..
>
>   
I meant that when the keys were necessarily freed when the linked list 
was destroyed, their lifetimes could be said to be tied to the list. 
With the avl tree the keys can be kept for other purposes after the tree 
is destroyed, thus they can `outlive' the tree. There was surely a 
better way to describe this.

Thanks for applying the patch! I'm now modifying the plugins to take 
advantage of the linked list.

Luke