PATCH: named address space support (1/2: target-independent parts)

[Ben Elliston]

Hi Joseph

Thanks for the review.  I've just dealt with all of the suggested
documentation changes (the easy bit) :-)

> @var is for metasyntactic variables, not for programming language text 
> (including names of programming language variables).  You mean 
> @code{__ea}.

OK.

> > +The @var{__ea} identifier may be used exactly like any other C type
> 
> @code{__ea}.

Fixed.

> > +qualifier (e.g. const or volatile).  See the N1169 document for more
> 
> "e.g." needs to be followed by a comma or by "@:".  @code{const}, 
> @code{volatile}.

Fixed.

> >  @deftypefn {Target Hook} bool TARGET_SCALAR_MODE_SUPPORTED_P (enum machine_mode @var{mode})
> > -Define this to return nonzero if the port is prepared to handle
> > -insns involving scalar mode @var{mode}.  For a scalar mode to be
> > -considered supported, all the basic arithmetic and comparisons
> > -must work.
> > +Define this to return nonzero if the port is prepared to handle insns
> > +involving scalar mode @var{mode}.  For a scalar mode to be considered
> > +supported, all the basic arithmetic and comparisons must work.
> 
> Don't mix reformatting this paragraph in with substantive unrelated 
> changes to the compiler.

This was an unitended paragraph fill in emacs.  I've reverted that hunk.

Cheers, Ben