Use sprintf instead of snprintf to retain compatibility on some arches

snprintf() is not available on some arm arches, and there's no desperate need
to use it in slim.

Ck.cpp

@@ -91,7 +91,7 @@ namespace Ck {
 
     vt = *((long *)return_value);
 
-    std::snprintf(device, 32, "/dev/tty%ld", vt);
+    std::sprintf(device, "/dev/tty%ld", vt);
 
     if(return_value)
       XFree(return_value);