package/x11r7/xdriver_xf86-video-siliconmotion: Fix compile warnings being treated as error

Fixes
http://autobuild.buildroot.net/results/059/059d771cb39532dee73a5f50e24b3441005ed38b/
http://autobuild.buildroot.net/results/542/5429dd3f07430cf1487a8cfa82ba55e66a640473/
http://autobuild.buildroot.net/results/073/073105a692033665d31b2dc034eff2e0fdca7f10/
http://autobuild.buildroot.net/results/018/01805d60b8b046122d357e2559268e8a45dcf9d3/
and many others

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/x11r7/xdriver_xf86-video-siliconmotion/xdriver_xf86-video-siliconmotion.mk

@@ -11,4 +11,6 @@ XDRIVER_XF86_VIDEO_SILICONMOTION_LICENSE = MIT
 XDRIVER_XF86_VIDEO_SILICONMOTION_LICENSE_FILES = COPYING
 XDRIVER_XF86_VIDEO_SILICONMOTION_DEPENDENCIES = xserver_xorg-server xproto_fontsproto xproto_randrproto xproto_renderproto xproto_videoproto xproto_xextproto xproto_xproto
 
+XDRIVER_XF86_VIDEO_SILICONMOTION_CONF_OPTS = --disable-selective-werror
+
 $(eval $(autotools-package))