queue template constructors uncallable

Using queue with an allocator, it is impossible to write code that invokes this template constructor:

```
template
queue(size_type n, typename node_allocator::template rebind::other const & alloc):
```

(or the other one with the rebind).

The template argument U cannot be deduced (at least with gcc 5.3.0).

I had to add the following form in order to use this with a custom allocator:

`explicit queue(size_type n, allocator const & alloc)`

I notice that the constructor that takes only an `alloc` already has this overload.

Start at the queue constructor overloads shown in the issue and compare them with the existing constructor that accepts only an allocator. Verify that constructing a queue with a size and custom allocator compiles without requiring an undeducible template argument; completion is demonstrated by a compiling regression test or equivalent build check.

Written by the indexing model from the issue text.