Fix compilation: uid_t, gid_t and pid_t are defined in sys/types.h
Fix compilation: uid_t, gid_t and pid_t are defined in sys/types.h

This error shows up in third-party code when including
wayland-server.h.

mchalupa/wayland,tulcod/wayland,abooij/wayland,sir-murray/wayland,tulcod/wayland,eyolfson/wayland,sir-murray/wayland,abooij/wayland,bitfactor/wayland,mchalupa/wayland,eyolfson/wayland,tulcod/wayland,abooij/wayland,mchalupa/wayland,bitfactor/wayland,bitfactor/wayland,eyolfson/wayland,sir-murray/wayland