Add := digraph to D

[Christophe Travert]

"Lars T. Kyllingstad" , dans le message (digitalmars.D:170381), a
> That said, I was still wrong. :)  I just tried it now, and 
> apparently you can write pointless stuff like "auto extern int 
> foo;" and DMD will compile it just fine.  (And, unless that is a 
> bug, it means D has redefined 'auto' to mean absolutely nothing, 
> except to be a marker saying "this is a declaration", allowing 
> one to omit both storage class and type.)

dlang.org states:

| Auto Attribute
| The auto attribute is used when there are no other attributes and type 
| inference is desired. 

So indeed, in a variable declaration, auto has no meaning other than 
saying "this is a declaration".

-- 
Christophe