[lib][cpp] add a auto_call class
[lib][cpp] add a auto_call class

useful for calling routines at the exit of a function.

hollanderic/lkstuff,hollanderic/lkstuff,littlekernel/lk,hollanderic/lkstuff,hollanderic/lkstuff,littlekernel/lk,littlekernel/lk,littlekernel/lk