coretypes.h: change class rtx_def to struct

[Richard Biener]

On Thu, 19 Jan 2017, Jakub Jelinek wrote:

> On Thu, Jan 19, 2017 at 12:23:34PM +0100, Richard Biener wrote:
> > On Thu, 19 Jan 2017, Gerald Pfeifer wrote:
> > 
> > > This innocent looking patch shaves 1749 warnings in stage 1
> > > when building with clang (such as on newer versions of FreeBSD).
> > > 
> > > Richi, at one point you indicated such changes would be fine
> > > (though usually they go from struct to class)?
> > 
> > In this case I'd rather prefer you make rtx_def a class (for consistency
> > with the other classes deriving from it).
> > 
> > That change is ok.
> 
> Wouldn't it be better to just in configure add -Wno-whatever to disable the
> bogus clang warning (if it has a -W* switch)?

Also works for me.

> Making rtx_def a class would require adding public:

Yes, but it would be consistent then.

Richard.