Remove unnecessary slob checks in lab5

Signed-off-by: Junjie Mao <eternal.n08@gmail.com>
Suppress output from 'make clean' in autotest

Signed-off-by: Junjie Mao <eternal.n08@gmail.com>
Solutions to lab5 (still buggy)

Signed-off-by: Junjie Mao <eternal.n08@gmail.com>