This fixes an incorrect sign extension in the compat layer that breaks
32bit shmget that are >2GB.  sys_shmget has a signed size_t size argument,
and the int size argument coming from 32bit user space would get sign
extended to 64bit, which is wrong.

I fixed it on all compat architectures, except PPC64 which was already ok. 

It was originally debugged and fixed by Karl Rister @ IBM for SLES9 on x86-64.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>