A página de erro de 2078 , mencionada no erro, mas não no número do link impresso, diz:
This message occurs with TLS netstream driver. For TLS, certificates (.pem files) are needed to provide security credentials. This error is issued if there is a problem with these files. The message contains a more precise error description. That error text is taken directly from the underlying TLS library.
A common cause is that the file can not be found or accessed (permissions!). In that case, a rsyslogd-2040 error will follow.
Além disso, se você verificar /usr/lib/rsyslog/
e lmnsd_gtls.so
realmente não existe, ele aponta para rsyslog-gnutls
possivelmente não sendo instalado.