New users need a wallpaper_file type.

Change-Id: I7ff4ed9f73f43918cac05a026af68cca8dbe02c3
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>

file_contexts

@@ -172,6 +172,8 @@
 /data/data/.*		u:object_r:app_data_file:s0
 # Wallpaper file.
 /data/data/com.android.settings/files/wallpaper	u:object_r:wallpaper_file:s0
+# Wallpaper file for other users
+/data/system/users/[0-9]+/wallpaper		u:object_r:wallpaper_file:s0
 #############################
 # efs files
 #