kbuild workaround for VirtualBox-OSE

[Sérgio Basto]

After Fedora rebuild kBuild with gcc 4.7, kmk_sed doesn't work
correctly. 
I reported upstream http://svn.netlabs.org/kbuild/ticket/112 .
I couldn't find any solution, but I found one workaround which is use
kBuild bundle in VirtualBox. 
May I do this exception until we find what happen to kBuild compiled
with gcc-4.7 ?

Note 1: I think kBuild will not have a different behavior.
Note 2: I like update VirtualBox on F17 and rawhide on move on testing
with new X11 version etc . I have done a Mesa patch or un-bundle more
X11 sources.

Thanks,
-- 
Sérgio M. B.