Very basic example codes.

- bbskel: BasicBlock pass skeleton
- cgspskel: CallGraphSCC pass skeleton
- comminute: tool illustrating pass mgr, pass deps, and more
- fpskel: FunctionPass skeleton
- intflip: integer argument randomizer|bit-flipper
- mpskel: ModulePass skeleton
- npassert: NULL pointer check insertion
- rpskel: RegionPass skeleton
- visitorskel: Using a InstVisitor class