[Patch] libstdc++/19495

[Benjamin Kosnik]

	* include/ext/array_allocator.h: Tweak slightly, avoid assuming
	the existence of an _Array::begin() member.

It's my preference to keep _M_array->size(), and _M_array->begin()
function calls in there please. When we have concepts, I'll add these
bits as a requirement. OK?

Anyway.

Any chance you can make a bugzilla entry about the array_allocator
rebind problem? It would be good if this issue does not get lost.

I like the v7 solution for this better. However, for so 6 this seems completely appropriate.

;)

best,
benjamin