build: Generated protocol files live in protocol/ now
build: Generated protocol files live in protocol/ now

Fix up the references in include_HEADERS.

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