journald: always allocate space for object fields

If OBJECT_PID= came as the last field, we would not reallocate the iovec to bigger size,
and fail the assertion later on in dispatch_message_real().

(cherry picked from commit 92ee6447b1)

src/journal/journald-native.c

@@ -133,7 +133,7 @@ void server_process_native_message(
                 /* A property follows */
 
                 /* n existing properties, 1 new, +1 for _TRANSPORT */
-                if (!GREEDY_REALLOC(iovec, m, n + 2 + N_IOVEC_META_FIELDS + !!object_pid * N_IOVEC_OBJECT_FIELDS)) {
+                if (!GREEDY_REALLOC(iovec, m, n + 2 + N_IOVEC_META_FIELDS + N_IOVEC_OBJECT_FIELDS)) {
                         log_oom();
                         break;
                 }