gnu: Use HTTPS for gnome.org and subdomains.

gnu: Use HTTPS for gnome.org and subdomains.

* gnu/packages/fonts.scm (font-bitstream-vera)[home-page]: Use HTTPS.
* gnu/packages/glib.scm (glib)[home-page]: Likewise.
* gnu/packages/gnome.scm (gcr, libgnome-keyring, gnome-keyring, evince)
(gnome-icon-theme, libgsf, gnome-mime-data, vala, vte, python2-rsvg)
(glib-networking, gnome-settings-daemon, libchamplain, grilo, grilo-plugins)
(gjs, zenity, mutter, network-manager, network-manager-applet, gdm)
[home-page]: Likewise.
* gnu/packages/gtk.scm (gtk-engines, murrine)[home-page]: Likewise.