Restore module loading

The module loading feature got broken a while ago, so restore it, but
have it a bit more explicit this time around.

Reviewed-by: Stephen Henson <steve@openssl.org>

apps/spkac.c

@@ -186,6 +186,8 @@ int spkac_main(int argc, char **argv)
 
     if ((conf = app_load_config(infile)) == NULL)
         goto end;
+    if (!app_load_modules(conf))
+        goto end;
 
     spkstr = NCONF_get_string(conf, spksect, spkac);