hashmap_get takes "const struct hashmap_entry *"

This is less error-prone than "const void *" as the compiler
now detects invalid types being passed.

Signed-off-by: Eric Wong <e@80x24.org>
Reviewed-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

config.c

@@ -1863,7 +1863,7 @@ static struct config_set_element *configset_find_element(struct config_set *cs,
 
 	hashmap_entry_init(&k.ent, strhash(normalized_key));
 	k.key = normalized_key;
-	found_entry = hashmap_get(&cs->config_hash, &k, NULL);
+	found_entry = hashmap_get(&cs->config_hash, &k.ent, NULL);
 	free(normalized_key);
 	return found_entry;
 }