syslog-ng: update to version 3.35.1

syslog-ng: update to version 3.35.1

Also bump the version in syslog-ng config file.
Removes this warning:

Nov 16 14:19:41 turris syslog-ng[15159]: WARNING: Configuration file format is too old, syslog-ng is running in compatibility mode. Please update it to use the syslog-ng 3.35 format at your time of convenience. To upgrade the configuration, please review the warnings about incompatible changes printed by syslog-ng, and once completed change the @version header at the top of the configuration file; config-version='3.33'

Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com>