[PATCH] powerpc: Merge futex.h

This patch merges the ppc32 and ppc64 versions of futex.h, essentially
by taking the ppc64 version as the powerpc version.  The old ppc32
version did not implement the futex_atomic_op_inuser() callback (it
always returned -ENOSYS), so FUTEX_WAKE_OP would not work on ppc32.
In fact the ppc64 version of this function is almost suitable for
ppc32 as well - the only change needed is to extend ppc_asm.h with a
macro expanding to to the right pseudo-op to store a pointer (either
".long" or ".llong").

Built and booted on pSeries.  Built for 32-bit powermac.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>