implement update proxy support for archlinux

network/update-proxy-configs

@@ -117,3 +117,8 @@ fi
 if [ -e /etc/PackageKit/PackageKit.conf ]; then
     update_conf /etc/PackageKit/PackageKit.conf "ProxyHTTP=$PROXY_ADDR"
 fi
+
+# Pacman (archlinux) also
+if [ -e /etc/pacman.conf ]; then
+    update_conf /etc/pacman.conf "XferCommand = http_proxy=$PROXY_ADDR /usr/bin/wget --passive-ftp -c -O %o %u"
+fi