[PATCH] lockdep: forward declare struct task_struct

[PATCH] lockdep: forward declare struct task_struct

3117df0453828bd045c16244e6f50e5714667a8a causes this:

In file included from arch/s390/kernel/early.c:13:
include/linux/lockdep.h:300: warning:
		"struct task_struct" declared inside parameter list
include/linux/lockdep.h:300:
		warning: its scope is only this definition or
		declaration, which is probably not what you want

Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>