main: Disable SSLv3 because of POODLE

Since GOA is still using WebKit1, we need to set the environment
variable ourself. We can stop setting it once we port to WebKit2
because the network process will handle it for us.

https://bugzilla.gnome.org/show_bug.cgi?id=739960

shell/main.c

@@ -37,6 +37,9 @@ main (int argc, char **argv)
   GtkApplication *application;
   int status;
 
+  /* FIXME: remove this when GOA uses WebKit2 */
+  g_setenv("G_TLS_GNUTLS_PRIORITY", "NORMAL:%COMPAT:!VERS-SSL3.0", FALSE);
+
   bindtextdomain (GETTEXT_PACKAGE, GNOMELOCALEDIR);
   bind_textdomain_codeset (GETTEXT_PACKAGE, "UTF-8");
   textdomain (GETTEXT_PACKAGE);