Warning fixes from Christos Zoulas

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

lib/hx509/collector.c

@@ -253,7 +253,8 @@ _hx509_collector_collect_certs(hx509_context context,
 			       hx509_certs *ret_certs)
 {
     hx509_certs certs;
-    int ret, i;
+    int ret;
+    size_t i;
 
     *ret_certs = NULL;
 
@@ -286,7 +287,7 @@ _hx509_collector_collect_private_keys(hx509_context context,
 				      struct hx509_collector *c,
 				      hx509_private_key **keys)
 {
-    int i, nkeys;
+    size_t i, nkeys;
 
     *keys = NULL;
 
@@ -315,7 +316,7 @@ _hx509_collector_collect_private_keys(hx509_context context,
 void
 _hx509_collector_free(struct hx509_collector *c)
 {
-    int i;
+    size_t i;
 
     if (c->unenvelop_certs)
 	hx509_certs_free(&c->unenvelop_certs);