Fix display misbehaving as a wpsetter.

ImageMagick's display returns 1 if it is to draw on the root window.
Teach awsetbg that this is not an error condition.

Signed-off-by: Nikos Ntarmos <ntarmos@cs.uoi.gr>
Signed-off-by: Julien Danjou <julien@danjou.info>

utils/awsetbg

@@ -510,7 +510,8 @@ fi
 
 
 $WPSETTER `eval echo $option` "$wallpaper"
-if [ $? -ne 0 ]; then
+if [ $? -ne 0 -a "$WPSETTER" != "display" ] ||
+   [ $? -ne 1 -a "$WPSETTER"  = "display" ]; then
     message "Something went wrong while setting the wallpaper.
 Run '$WPSETTER "`eval echo $option` $wallpaper"' from an xterm to find out what."
     exit 1