[PATCH] Remove volatile qualifiers from mt_allocator

[Paolo Carlini]

Paolo Carlini wrote:

> FYI, now I know a much better way to fix this, meaning: 1- No atomic 
> operations at allocation time, minimal performance impact; 2- Safe wrt 
> old binaries linking to the current version of the exported functions 
> of mt_allocator (I'm not changing anything in mt_allocator.h, nothing 
> in the exported interfaces of mt_allocator.cc, etc...). I should have 
> something well tested in a day or two max :)

As I said, I'm not going to touch mt_allocator.h, but eventually I will 
probably add a comment to the declaration of _M_used, therefore, I'm 
going to commit first Richard' clean-up (I'm also doing all the tests 
with that patch applied before mine...)

Paolo.