Micro optimizations welcome?

[Ursache Vladimir]

 Hi,
On amd64 struct wl_display from wayland-client.c can shrink in size
from 320 bytes to 304 if two fields (last_error and id) are
rearranged. Compiles fine.

End result looks like this:

struct wl_display {
    struct wl_proxy proxy;
    struct wl_connection *connection;

    /* When display gets an error event from some object, it stores
     * information about it here, so that client can get this
     * information afterwards */
    struct {
        /* Code of the error. It can be compared to
         * the interface's errors enumeration. */
        uint32_t code;
        /* id of the proxy that caused the error. There's no warranty
         * that the proxy is still valid. It's up to client how it will
         * use it */
        uint32_t id;
        /* interface (protocol) in which the error occurred */
        const struct wl_interface *interface;
    } protocol_error;
    /* errno of the last wl_display error */
    int last_error;
    int fd;
    struct wl_map objects;
    struct wl_event_queue display_queue;
    struct wl_event_queue default_queue;
    pthread_mutex_t mutex;

    int reader_count;
    uint32_t read_serial;
    pthread_cond_t reader_cond;
};