lighttpd: run as non-privileged user www-data

Previously the stock lighttpd configuration was patched to run as user root,
because we do not have a lighttpd user.
Patch it to use www-data instead, which is a user available in the default
skeleton, and is the same other webserver packages (like nginx) use.

Signed-off-by: Floris Bos <bos@je-eigen-domein.nl>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/lighttpd/0001-Fix-default-config-file.patch

@@ -51,8 +51,8 @@ diff -Nurp a/doc/config/lighttpd.conf b/doc/config/lighttpd.conf
  ##
 -server.username  = "lighttpd"
 -server.groupname = "lighttpd"
-+# server.username  = "lighttpd"
-+# server.groupname = "lighttpd"
++server.username  = "www-data"
++server.groupname = "www-data"
  
  ## 
  ## enable core files.