[patch, fortran] Make frontend walker more general

[Thomas Koenig]

Hi Jakub,

> > 
> > Given the complexity of Fortran, wouldn't this lead to lots of code
> > duplication, with a big switch statement both in the statement walker
> > and the handler for the individual statements?
> 
> Because otherwise it isn't a general Fortran FE walker, but quite
> specialized one, and each time you need to handle some code that doesn't
> have a hook or where the hook doesn't have generic enough argument,
> you will need to modify the walker.
> 
> I believe in most cases you'll be looking only at a handful of different
> codes, so even if you use a switch stmt in the hook, it will be small enough
> that it will be implemented using a series of ifs.

OK, I withdraw the patch then.

	Thomas