strace-graph: cope with clone immediately followed by exit
strace-graph: cope with clone immediately followed by exit

* strace-graph: A clone() followed by exit() with no intervening fork
or execve resulted in the new pid having no seq key.  That breaks when
trying to use seq as an array reference.  Ensure that clone populates
the new pid with an empty seq entry.

cuviper/strace,Saruta/strace,Saruta/strace,cuviper/strace,Saruta/strace,cuviper/strace,Saruta/strace,Saruta/strace,cuviper/strace,cuviper/strace