Support for %d$c format specifier in diagnostics.c

[Gabriel Dos Reis]

Ishikawa <ishikawa@yk.rim.or.jp> writes:

[...]

| I think I will create the functional interface to request the type
| information to
| the custom decoder, etc. and modify
| cp/error.c and c_tree_printer routine.
| I hope these file (cp/error.c) and routine (c_tree_printer)
| are not in the state of active modification.

They are.  Especially, we should start slowly using much rational
tree pretty-printers once I'm finished with getting of xxx_with_decl.

At that point, tree printers couold be asked to render a tree at a
time. I expect that at some point, RTL diagnostics will also use that
framework, and other part of the compiler switch to that scheme.

-- Gaby