Warning fixes from Christos Zoulas

- shadowed variables
- signed/unsigned confusion
- const lossage
- incomplete structure initializations
- unused code

lib/hx509/ks_dir.c

@@ -202,16 +202,12 @@ dir_iter_end(hx509_context context,
 
 
 static struct hx509_keyset_ops keyset_dir = {
-    "DIR",
-    0,
-    dir_init,
-    NULL,
-    dir_free,
-    NULL,
-    NULL,
-    dir_iter_start,
-    dir_iter,
-    dir_iter_end
+    .name = "DIR",
+    .init = dir_init,
+    .free = dir_free,
+    .iter_start = dir_iter_start,
+    .iter = dir_iter,
+    .iter_end = dir_iter_end,
 };
 
 void