[PATCH, ADA, DOC]: PR 15479: nice brackets

[Arnaud Charlet]

> While the PR has been closed for good, as most issues have been
> addressed, there are a few leftover bits.  This is one of them:
> nice brackets around optional data or parameters.
> 
> Tested 'make info html pdf'.  OK for trunk?
> 
> Thanks,
> Ralf
> 
> gcc/ada/ChangeLog:
> 2008-07-06  Ralf Wildenhues  <Ralf.Wildenhues@gmx.de>
> 
> 	PR documentation/15479
> 	* gnat_ugn.texi (@ovar): New macro, from autoconf.texi.
> 	Replace backets around optional parameters with @ovar
> 	where possible, use @r{[}, @r{]} otherwise.
> 	Replace some @r, @i, and @emph with @var where appropriate.

OK, thanks.

Arno