(garbage) ptrace events like
    ... apparmor="DENIED" operation="ptrace" profile="/bin/netstat" pid=1962 comm="netstat" target=""
cause an empty name2 field, which leads to a crash in the tools.

This patch lets logparser.py ignore such garbage log events, which also
avoids the crash.

As usual, add some testcases.

test-libapparmor-test_multi.py needs some special handling to ignore the
empty name2 field in one of the testcases.


References: https://bugs.launchpad.net/apparmor/+bug/1689667


Acked-by: Seth Arnold <seth.arnold@canonical.com> for trunk and 2.11.

Older releases can't handle ptrace log events and therefore can't crash ;-)