Add missing symbols for versioned namespace

[Jonathan Wakely]

On 03/11/16 21:54 +0100, François Dumont wrote:
>Hi
>
>    I might not be the right one to propose this patch as I am not 
>sure that I fully understand gnu-versioned-namespace.ver organization. 
>But with it following test failures when using versioned namespace 
>vanish:
>
>FAIL: 20_util/allocator/overaligned.cc (test for excess errors)
>FAIL: ext/bitmap_allocator/overaligned.cc (test for excess errors)
>FAIL: ext/mt_allocator/overaligned.cc (test for excess errors)
>FAIL: ext/new_allocator/overaligned.cc (test for excess errors)
>FAIL: ext/pool_allocator/overaligned.cc (test for excess errors)
>
>    Ok to commit ?

This looks correct. OK for trunk, thanks.