compiler_wrapper portgroup

[Joshua Root]

Recently, quite a lot of changes have been made to a number of 
portgroups, eventually ending up with a new compiler_wrapper portgroup 
which is now included by several others.

Chris, for those who have not kept up with all the changes, would you be 
able to explain what problems all this is solving, how it solves them, 
and why this particular approach was chosen?

- Josh