mesa3d-demos: select libglew/libglu if needed

Fixes:
http://autobuild.buildroot.net/results/4b1/4b16c9797c653c248725a55d9b8eafc4634b968c/build-end.log

libglew/libglu are added to _DEPENDENCIES for X11+GL, but not selected at
the kconfig level.

While we're at it, correct the dependencies for the X11 selects as well
(only used if GL is available).

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/mesa3d-demos/Config.in

@@ -1,7 +1,9 @@
 config BR2_PACKAGE_MESA3D_DEMOS
 	bool "mesa3d-demos"
-	select BR2_PACKAGE_XLIB_LIBX11 if BR2_PACKAGE_XORG7
-	select BR2_PACKAGE_XLIB_LIBXEXT if BR2_PACKAGE_XORG7
+	select BR2_PACKAGE_LIBGLEW if BR2_PACKAGE_XORG7 && BR2_PACKAGE_HAS_LIBGL
+	select BR2_PACKAGE_LIBGLU if BR2_PACKAGE_XORG7 && BR2_PACKAGE_HAS_LIBGL
+	select BR2_PACKAGE_XLIB_LIBX11 if BR2_PACKAGE_XORG7 && BR2_PACKAGE_HAS_LIBGL
+	select BR2_PACKAGE_XLIB_LIBXEXT if BR2_PACKAGE_XORG7 && BR2_PACKAGE_HAS_LIBGL
 	depends on BR2_PACKAGE_HAS_LIBGL || BR2_PACKAGE_HAS_LIBGLES \
 		|| BR2_PACKAGE_HAS_LIBEGL || BR2_PACKAGE_HAS_LIBOPENVG
 	help