textproc/augeas: Fix rsyslog lense

This integrate the PR863 that fixes parsing of rsyslogd.conf
files with "if xxx then {}".

PR: 287586
Approved by: 0mp (mentor)
Approved by: maintainer timeout
Sponsored by: Klara, Inc.
Obtained from: https://github.com/hercules-team/augeas/pull/863
Differential Revision: https://reviews.freebsd.org/D50873