This fixes the build on Debian Wheezy which otherwise fails with:
CC libvirt_driver_lxc_impl_la-lxc_process.lo
lxc/lxc_process.c: In function 'virLXCProcessGetNsInode':
lxc/lxc_process.c:648:5: error: implicit declaration of function 'stat' [-Werror=implicit-function-declaration]
lxc/lxc_process.c:648:5: error: nested extern declaration of 'stat' [-Werror=nested-externs]
cc1: all warnings being treated as errors