Otherwise it fails like so:
CC egl_dri2.lo
In file included from egl_dri2.h:40:0,
from egl_dri2.c:42:
../../../../../../src/egl/wayland/wayland-drm/wayland-drm.h:8:41:
fatal error: wayland-drm-server-protocol.h: No such file or directory
compilation terminated.
-I$(top_srcdir)/src/gbm/backends/dri \
-I$(top_srcdir)/src/egl/wayland/wayland-egl \
-I$(top_srcdir)/src/egl/wayland/wayland-drm \
+ -I$(top_builddir)/src/egl/wayland/wayland-drm \
$(DEFINES) \
$(LIBDRM_CFLAGS) \
$(LIBUDEV_CFLAGS) \