package/libxml2: change download site to http

ftp is blocked on some (corporate) networks.

Signed-off-by: Nityananda Padhan <ntneitin@gmail.com>
Reviewed-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libxml2/libxml2.mk

@@ -5,7 +5,7 @@
 ################################################################################
 
 LIBXML2_VERSION = 2.9.9
-LIBXML2_SITE = ftp://xmlsoft.org/libxml2
+LIBXML2_SITE = http://xmlsoft.org/sources
 LIBXML2_INSTALL_STAGING = YES
 LIBXML2_LICENSE = MIT
 LIBXML2_LICENSE_FILES = COPYING