MetaIO: Add missing include <stddef.h> for ptrdiff_t
MetaIO: Add missing include <stddef.h> for ptrdiff_t

Fixes error "ptrdiff_t was not declared in this scope".

Author: David Doria <daviddoria@gmail.com>
Change-Id: I1e0dee67d26681f4119ac1fd00ecec3d139eb726

SVN-Revision: 3543
opoplawski/MetaIO,tjcorona/MetaIO,opoplawski/MetaIO,tjcorona/MetaIO