From: Christoph Hellwig <hch@lst.de>

asm-ppc/elf.h uses a pointer to struct task_struct without any
forward-declaration.

In file included from include/linux/elf.h:5,
                 from arch/ppc/boot/simple/misc.c:20:
include/asm/elf.h:102: warning: `struct task_struct' declared inside parameter list
include/asm/elf.h:102: warning: its scope is only this definition or declaration, which is probably not what you want