From: Dietmar Maurer <dietmar@proxmox.com>

The signalfd function prototype and the signalfd header file is not
defined in the debian Lenny. We want to use this debian version with a
newer kernel.

This patch gives the signalfd function prototype, because the function is
available in the glibc-2.7 which is the version coming with debian Lenny.
Signed-off-by: Dietmar Maurer <dietmar@proxmox.com>
Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>