bug#27584: 26.0.50; alist-get: Add optional arg TESTFN

[Tino Calancha <tino.calancha@gmail.com>]

On Thu, 6 Jul 2017, Nicolas Petton wrote:

> Tino Calancha <tino.calancha@gmail.com> writes:
>
>>> It's been called cl-assoc so far ;-)
>
>> Some day your dream will be fulfilled, and `cl-lib' will be preloaded at
>> startup.  Then, we will not need things like `assoc-predicate'.
>
> map.el could require cl-lib and use cl-assoc?
Actually, it already does require cl-lib, because the following chain:
* map.el requires `seq'
* seq.el requires `cl-lib'

Indeed, in my patch `assoc-predicate' doesn't appear in map.el,
so it's not just a matter of replace:
assoc-predicate ---> cl-assoc

`assoc-predicate' appears in the implementation (subr.el)
and setter expansion (gv.el) of `alist-get'.

Neither subr.el nor gv.el are requiring `cl-lib'.