Try to find a compiler option that warns when a stringliteral is
used in a place that could potentially modify the address. This
should warn on giving an stringliteral to a function that asks of
a non-const-modified char-pointer.
The sanity check is done by looking at string.h which has a set
of strcpy definitions that should be defined with const-modifiers
to not emit a warning in all so many places.
Currently this macro knows about GCC.
hopefully will evolve to use: Solaris C compiler,
Digital Unix C compiler, C for AIX Compiler, HP-UX C compiler,
and IRIX C compiler.