[C++ PATCH] Improve ?: operator error messages.

[Gabriel Dos Reis]

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

| This patch simply improves the error messages when the two last operands
| of a ?: are of different types. This brings the messages used in
| templated methods/functions on par with those used for regular
| methods/functions.

OK.

-- Gaby