[PATCH] Fix warnings for WARN_ON if CONFIG_BUG is disabled

In most cases the return value of WARN_ON() is ignored.  If the generic
definition for the !CONFIG_BUG case is used this will result in a warning:

  CC      kernel/sched.o
In file included from include/linux/bio.h:25,
                 from include/linux/blkdev.h:14,
                 from kernel/sched.c:39:
include/linux/ioprio.h: In function â\80\98task_ioprioâ\80\99:
include/linux/ioprio.h:50: warning: statement with no effect
kernel/sched.c: In function â\80\98context_switchâ\80\99:
kernel/sched.c:1834: warning: statement with no effect

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>