make all vs make bootstrap

[Ben Elliston]

Hi Paolo

> It supports all the bells and whistles like bubblestraps and
> restageN, which help during development. make restrap (taking a
> non-bootstrap build and using it as stage1) is not supported. make
> restageN is called make all-stageN, and there is also make
> all-stageN-gcc to rebuild gcc only. There is no equivalent to
> quickstrap, even though it can be added if there's demand.

I see that gcc/doc/makefile.texi is now out of date.  Can you update
it so that we have a reference for the new targets?  Thanks,

Ben