Some extra decorations

[Paolo Carlini]

Hi,
> I am now looking if I can get the warnings into low enough noise so it
> can be used by default.  There are some problems with that, in
> particular stuff in throw_condtioinally defined in throw-allocator.h
> It seems to be plain externally visible function that is defined in
> system header.  Why we do so?
> It don't seem to be exported from libstdc++ nor useful in application
> (i.e. if I include throw-allocator in multiple source files I get link
> error).  How these headers are supposed to be used?
>   
Benjamin probably knows better about this allocator, certainly, as-is,
you are right there is something wrong with those functions, because
defined out-of-line.

Patch is ok, thanks!

Paolo.