powerpc: Merge thread_info.h

[Christoph Hellwig]

On Fri, Oct 21, 2005 at 03:45:50PM +1000, David Gibson wrote:
> 	- In readiness for 64k pages, when THREAD_SIZE will be less
> than a page, ppc64 used kmalloc() rather than get_free_pages() to
> allocate the kernel stack.  With this patch we do the same for ppc32,
> since there's no strong reason not to.

This adds quite a bit of overhead and wasted memory.  Please don't do it
for ppc32 or ppc64 with THREAD_SIZE >= PAGE_SIZE either.