desktop-shell: no need to unset WAYLAND_SOCKET

As of commit "client: unset WAYLAND_SOCKET env variable",
58bb064afa3bfc706e3b30dd170804235aa272ea, in the Wayland core, the
Wayland library will unset the environment variable automatically.

No need to explicitly unset it again here.

Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>

clients/desktop-shell.c

@@ -606,9 +606,6 @@ int main(int argc, char *argv[])
 		return -1;
 	}
 
-	/* The fd is our private, do not confuse our children with it. */
-	unsetenv("WAYLAND_SOCKET");
-
 	wl_display_add_global_listener(display_get_display(desktop.display),
 				       global_handler, &desktop);