Proposed doc update for Explicit Reg Vars 1/3

[David Wohlferd]

> Abot the patches themselves...  Hard to review again, sigh...

I know, and I'm sorry.

I just can't see any way to completely re-org the text without the patch 
becoming a nightmare.  I was hoping the html links would make that 
easier, but I guess not.  On the plus side, Explicit reg vars is the 
last section I plan to do this to.  I appreciate you taking the time.

>> The current menu page has a couple of flaws:
>>
>> 1) It tries to condense the entire contents of the other 2 pages into a
>> single paragraph each.  This loses a lot of detail and nuance, as well
>> as introducing unnecessary duplication of information with the subpages.
> It provides an introduction, which is quite helpful in this case.  Without
> some blurb the two-entry menu looks silly too.
>
> Can you move the intro to the separate pages instead of losing it altogether?

I did keep a small amount of intro on the the menu page.  If you feel 
there's more that we should keep, I'm certainly willing to re-visit 
this.  Perhaps after we resolve the local/global stuff so we know what 
we really want to say.

Jeff has already checked in the patch for this menu page (but not the 
Local or Global subpages), so you can see what I've left here on the gcc 
website 
(https://gcc.gnu.org/onlinedocs/gcc/Explicit-Register-Variables.html).

> Two spaces after a full stop

Oops.<sp><sp>Again.<sp><sp>You can probably just automatically add this 
to every review you send me.  It's just so automatic for me to type this 
way.  In my (feeble) defense, the original text had this too.

Lastly, if some external website is linking to "Explicit Reg Vars", what 
do we want to have happen now that we have renamed that to "Explicit 
Register Variables"?  Should the link just fail?  I've added the @anchor 
so it doesn't, but I'm not sure that's the standard for gcc.  Who should 
I be asking?

dw