[PATCH] kbuild: revert "fix make -jN with multiple targets with O=..."

Commit 296e0855:

    "kbuild: fix make -jN with multiple targets with O=..."

causes a ~95% increase in build time for the kernel.  Before: 4m21s
after: 8m1.403s.  Can we revert this until another approach is found?

Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>