[PATCH] Increase AT_VECTOR_SIZE

On PowerPC, we want to be able to provide an AT_PLATFORM aux table
entry to userspace, so that glibc can choose optimized libraries for
the processor we're running on.  Unfortunately that would be the 21st
aux table entry on powerpc, meaning that the aux table including the
terminating null entry would overflow the mm->saved_auxv[] array,
leading to userland programs segfaulting.

This increases the size of the mm->saved_auxv array to be large enough
to accommodate an AT_PLATFORM entry on powerpc.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>