package/efl: fix build with wepb

webpdemux support in webp is mandatory since version 1.25.0 and
https://github.com/Enlightenment/efl/commit/df06418b6f39f3b8d73631bda33308b67736bb9d

Fixes:
 - http://autobuild.buildroot.org/results/736357e669c35bd56e818c0c7fabd1b455f40a5f

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Reviewed-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/efl/Config.in

@@ -256,6 +256,7 @@ config BR2_PACKAGE_EFL_TIFF
 config BR2_PACKAGE_EFL_WEBP
 	bool "libevas webp image loader"
 	select BR2_PACKAGE_WEBP
+	select BR2_PACKAGE_WEBP_DEMUX
 	help
 	  This enables the loader code that loads images using WebP.