Block original umount syscall in default seccomp filter
Block original umount syscall in default seccomp filter

The original umount syscall without flags argument needs to
be blocked too.

Signed-off-by: Justin Cormack <af64ee19f04db9509cb02b0e470e11e5402ef9b3@unikernel.com>

aditirajagopal/docker,aditirajagopal/docker,aditirajagopal/docker