[Bug libstdc++/56019] max_align_t should be in std namespace

[Jobst.Ziebell at mailbox dot tu-dresden.de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56019

Jobst.Ziebell at mailbox dot tu-dresden.de changed:

           What    |Removed                     |Added
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                 CC|                            |Jobst.Ziebell at mailbox dot tu-dr
                   |                            |esden.de

--- Comment #4 from Jobst.Ziebell at mailbox dot tu-dresden.de ---
The fix introduces another problem. Whenever '__need_size_t' is defined prior
to the inclusion of <cstddef>, the type 'max_align_t' will not have been
defined.
This inevitably causes a compiler error:

#define __need_size_t
#include <cstddef>

int main( void )
{
    return 0;
}

This happens on Mac OS X 10.9. In my case it got triggered by including
<gmp.h>.
Presumably this bug also occurs when #defining the other '__need_*' macros.