[C++ PATCH] Make parser revert digraph "<:"

[Gabriel Dos Reis]

Theodore Papadopoulo <Theodore.Papadopoulo@sophia.inria.fr> writes:

| That being said, for the problem at hand it might be an overkill and the 
| scheme has also to be tested when there are other syntax errors 
| further in the program.

For the problem at hand, we know what the value of the token is.  It
is the value of the token '['.  The issue is to determine whether it
was spelt '[' or '<:' for diagnostic purpose only.  So, it is not a
case where we really have a tentative parsing.

-- Gaby