xwayland: keep temp files out of the client mask

Xwayland opens anonymous files for its sharing buffers, move these
file descriptors out of the range of the client select mask to avoid
reaching the maximum number of clients prematurely.

https://bugs.freedesktop.org/show_bug.cgi?id=91072

Tested-by: Olivier Fourdan <fourdan@gmail.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

hw/xwayland/xwayland-shm.c

@@ -82,7 +82,7 @@ create_tmpfile_cloexec(char *tmpname)
     }
 #endif
 
-    return fd;
+    return os_move_fd(fd);
 }
 
 /*