loggen: fix no-framing option

Signed-of-by: Tibor Benke <btibi@balabit.hu>
avro: empty pid field in a logmsg won't be serialized

Signed-off-by: Tibor Benke <btibi@balabit.hu>
avro: memory leak	bug fix

This patch contains a fix for memory leak caused by improper use of Avro
reference counting.

Signed-off-by: Tibor Benke <btibi@balabit.hu>