libc: make socketpair(3) use the right device
libc: make socketpair(3) use the right device

UDS expects the device number of the actual socket, not the device on
which the socket happens to reside.  The code worked only because PFS
returned the same value in the st_dev stat field, which it will have
to continue doing for a while now.

Change-Id: I426d38a86a96307ff6e6ed8099d37dae02d6bf2b

veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi