Remove unnecessary slob checks

Signed-off-by: Junjie Mao <eternal.n08@gmail.com>
Ignore fs image directory

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>