char* arguments in C API

[Martin v. Löwis]

> Even in C++, a special case for silent conversions of string literals to
> char * is provided.  The code should compile fine on both C and C++
> compilers.

While this conversion is well-formed, it is also deprecated. Atleast the
SunPro compiler warns if the conversion is used (and "all" warnings are
activated).

Regards,
Martin