[RFC] Update Stage 4 description

[Joseph Myers]

On Wed, 9 Jan 2019, Paul Koning wrote:

> Is there, or should there be, a distinction between primary and 
> non-primary platforms?  While platform bugs typically require fixes in 
> platform-specific code, I would think we would want to stay away from 
> bugfixes in minor platforms during stage 4.  The wording seems to say 
> that I could fix wrong-code bugs in pdp11 during stage 4; I have been 
> assuming I should not do that.  Is this something that should be 
> explicitly stated?

In target-specific code for a minor target you can more or less do as you 
want - but the decision on when to branch won't take account of what 
you're doing for a minor target, so any major work runs the risk of the 
branch happening at an unstable point in the middle of that work.

-- 
Joseph S. Myers
joseph@codesourcery.com