control script, make parallel builds the only way to do it
(facilitated by the taskrunner module) split out the guts of build-all
into separate scripts, etc.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@30377 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
