Makes the UML build system work well even under parallel make (tested, so far,
even with -j50).  Please notice that it must be updated for every makefile
change.  Or better, every makefile change must use correct dependencies (and
they are easy to miss).
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade_spam@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>