wayland: new socket addition

[Marek Chalupa]

Hi,

After the new patches for socket automatic naming the socket test, 
namely socket_path_overflow_server_create, fails. Probably introduced in 
79b1d2039aeb77b712cf4e1bb4049ebf9c453b59. It does not set errno as expected:

error: socket path 
"/run/user/1000/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" 
plus null terminator exceeds 108 bytes
lt-socket-test: tests/socket-test.c:83: 
socket_path_overflow_server_create: Assertion `(*__errno_location ()) == 
36' failed.
zsh: abort      ./socket-test socket_path_overflow_server_create

Moreover, there's a bug. When you add a socket, then add the same socket 
again, the original socket is removed, i. e.:

     /* OK */
     wl_display_add_socket(display, "wayland-0");

     /* this call fails and will delete the original socket */
     wl_display_add_socket(display, "wayland-0");

I wrote tests for it, sending them right away.

And one more thing... well, rather idea. Maybe it'd be nice to print:

    unable to lock lockfile /run/user/1000/wayland-0.lock, maybe another 
compositor is running
    unable to lock lockfile /run/user/1000/wayland-1.lock, maybe another 
compositor is running
    unable to lock lockfile /run/user/1000/wayland-2.lock, maybe another 
compositor is running
     .... etc. ...

only when manually adding the socket. It's really annoying when the 
terminal gets flooded
by 30 lines of this. But it's not a big deal either.


Regards,
Marek Chalupa