Updates to FFI spec

[Simon Marlow]

> > At the moment, there are two kinds of initialisation done for each
> > module:
> 
> Both ELF and DLLs on Windows provide a way of specifying initializers.
> 
> Or, easier yet, since the user is already using the hs_init function,
> you could use that.  The way you'd do that in ELF is to define a
> special section 'hs_initializers'.  Every module would contain a
> single object in that section: the address of the initializer.  (In
> gcc you do this by attaching an attribute to the variable.  In asm it
> is even easier since assemblers directly expose sections to the
> programmer.)  The linker will do what it does with all sections:
> concatenate the pieces from all object files.  hs_init would treat the
> section as an array of function pointers.  I'm sure that the Windows
> linker must have a similar mechanism - the main trick is figuring out
> what name to give the sections.

That's what I meant by a linker set :-)

Cheers,
	Simon