make clean: now removes all files except the pool directory from build directory
make clean: now removes all files except the pool directory from build directory


Former-commit-id: a6d28051f19a389b554a2cc2d73a672c96d169ab
dividiti/pencil-benchmark,dividiti/pencil-benchmark,pencil-language/pencil-benchmark,pencil-language/pencil-benchmark,pencil-language/pencil-benchmark,dividiti/pencil-benchmark,rbaghdadi/pencil-benchmark,rbaghdadi/pencil-benchmark,rbaghdadi/pencil-benchmark