[Predef-contribute] Dinkumware

[Mark J. <ma...@ja...>]

On https://sourceforge.net/p/predef/wiki/Libraries/, the macro for
Dinkumware is given as __CPPLIB_VER (two leading underscores) but MSVC2010,
MSVC2008, and the licensed copy of Dinkumware used by a codebase I work in
all seem to use _CPPLIB_VER (one leading underscore).  Could you please
review and update if appropriate?  Thanks,

Mark.