3.4 PATCH: Don't use #include "file.h" for system headers in Ada

[Arnaud Charlet]

> AFAIKT, adadecode.c is only linked into gnat1, so the ctype.h can be
> removed (since system.h already includes safe-ctype.h) and the single
> instance of isdigit converted to ISDIGIT.

adadecode.c is designed to be used anywhere an Ada decoder is needed,
so you need to keep the include <ctype.h> when not building gcc.

Arno