pos can never be less than 0 as it's of type size_t

Also fix the type which is passed in from various places.

src/acl.c

@@ -309,7 +309,7 @@ check_acl(int fd, const char *ip, const char *host)
 {
         struct acl_s *acl;
         int perm;
-        int i;
+        size_t i;
 
         assert(fd >= 0);
         assert(ip != NULL);

src/log.c

@@ -203,7 +203,7 @@ send_stored_logs(void)
 
         int level;
 
-        int i;
+        size_t i;
 
         for (i = 0; i != vector_length(log_message_storage); ++i) {
                 string = vector_getentry(log_message_storage, i, NULL);

src/reqs.c

@@ -106,7 +106,7 @@ add_connect_port_allowed(int port)
 static int
 check_allowed_connect_ports(int port)
 {
-        ssize_t i;
+        size_t i;
         int *data;
 
         /*

src/vector.c

@@ -180,7 +180,7 @@ vector_getentry(vector_t vector, size_t pos, size_t * size)
         struct vectorentry_s *ptr;
         size_t loc;
 
-        if (!vector || pos < 0 || pos >= vector->num_entries)
+        if (!vector || pos >= vector->num_entries)
                 return NULL;
 
         loc = 0;