InlineX::C2XS - create an XS file from an Inline C file.

The C file that InlineX::C2XS needs to find would contain
only the C code.

InlineX::C2XS looks for the file in ./src directory - expecting that the
filename will be the same as what appears after the final '::' in the
module name (with a '.c' extension). ie if the module is called
My::Next::Mod it looks for a file ./src/Mod.c, and creates a file
named Mod.xs. Also created, is the file 'INLINE.h' - but only if that
file is needed. The generated xs file (and INLINE.h) will be written
to the cwd unless a third argument (specifying a valid directory) is
provided to the c2xs() function.

The created XS file, when packaged with the '.pm' file, an
appropriate 'Makefile.PL', and 'INLINE.h' (if it's needed),
can be used to build the module in the usual way - without
any dependence upon the Inline::C module.