Handle more cases gracefully during printing, where not all the fields are
present for some of the records.

This makes the original commit 29d85950 ("parser.py: add an option for
printing") more robust and fixes a bug in the first hardening attempt of
commit f153e735

 ("parser.py: more robust printing").

Signed-off-by: Vincent Stehlé <vincent.stehle@arm.com>