weston: disable v4l simple dmabuf for headers < 3.8

It uses VIDIOC_EXPBUF which only came to light with kernel 3.8, so
disable it if headers are older. Fixes:
http://autobuild.buildroot.net/results/7fb/7fb9968b13f144c4576b28ecd01c82b74e4ed9d5/

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/weston/weston.mk

@@ -28,6 +28,11 @@ WESTON_CONF_OPTS = \
 WESTON_MAKE_OPTS = \
 	WAYLAND_PROTOCOLS_DATADIR=$(STAGING_DIR)/usr/share/wayland-protocols
 
+# Uses VIDIOC_EXPBUF, only available from 3.8+
+ifeq ($(BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_8),)
+WESTON_CONF_OPTS += --disable-simple-dmabuf-v4l-client
+endif
+
 ifeq ($(BR2_PACKAGE_DBUS),y)
 WESTON_CONF_OPTS += --enable-dbus
 WESTON_DEPENDENCIES += dbus