Changes

contrib/jenkins.sh: fix build: add --disable-syslog-logging

Since recently (see the related patch), libosmocore requires header
file syslog.h to be present, unless --disable-syslog-logging is given.

Change-Id: Ia49709dfebdf22cb00f70d667c996c3fbb8a1f51
Related: libosmocore.git Ifc54d60e24547696b3059b6eb75572f8c84874d0