futex: Fix compat_futex to be same as futex for REQUEUE_PI

Need to add the REQUEUE_PI checks to the compat_sys_futex API
as well to ensure 32 bit requeue's work fine on a 64 bit
system. Patch is against latest tip

Signed-off-by: Dinakar Guniguntala <dino@in.ibm.com>
Cc: Darren Hart <dvhltc@us.ibm.com>
LKML-Reference: <20090810130142.GA23619@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>