Less good ;-) results from Rittle's string allocator

[Loren James Rittle]

> More specifically, how often will memory clients /other than basic_string/
> be requesting chunks of a half-K at a time?
[...]
> Let me throw out an idea I had while typing the last paragraph:  we could
> make the _MAX_BYTES a template parameter of the allocator:

> old:      __default_alloc_template<true,0>
> new:      __default_alloc_template<true,0, _MAX_BYTES=256>

> or something similar.  Then basic_string can have its own memory pool.

Yuck was the first thing to come to my mind.  BTW, did you see the
comment that, under the current implementation, you can't just change
_MAX_BYTES?