[PATCH] Add scripts/backport-support.sh

[Florian Weimer]

* Florian Weimer:

> On 02/09/2017 11:35 PM, Adhemerval Zanella wrote:
>> I do not have a strong opinion here, but this workflow in the patch is
>> basically a simple git workflow. Do we really need backup this? Shouldn't
>> we just add this kind of documentation on wiki?
>
> I think having this in a script ensures that the backports are consistent.
>
> We also may have to blacklist backporting certain wrappers which use 
> functionality which is not available on older branches.

Any further comments?  Thanks.