fix(UDL): don't compare with address

cache_entry.c: In function '_cache_entry_add_new_attribute':
cache_entry.c:522:13: error: the comparison will always evaluate as 'true' for the address of 'name' will never be NULL [-Werror=address]
  522 |         if (!&attr->name) {
      |             ^
In file included from cache_entry.c:46:
cache_entry.h:53:15: note: 'name' declared here
   53 |         char *name;
      |               ^~~~
cc1: all warnings being treated as errors

Bug #56533

management/univention-directory-listener/src/cache_entry.c

@@ -519,7 +519,7 @@ static CacheEntryAttribute *_cache_entry_add_new_attribute(CacheEntry *entry, LD
 	entry->attributes = tmp;
 
 	BER2STR(&ava->la_attr, &attr->name);
-	if (!&attr->name) {
+	if (!attr->name) {
 		univention_debug(UV_DEBUG_LISTENER, UV_DEBUG_ERROR, "%s:%d BER2STR() failed", __FILE__, __LINE__);
 		goto error;
 	}