net-mgmt/icinga2: unbreak with boost 1.67

In file included from lib/base/base_unity.cpp:61:
lib/base/timer.cpp:269:31: error: no matching conversion for functional-style cast from 'double' to 'boost::posix_time::milliseconds' (aka 'subsecond_duration<boost::posix_time::time_duration, 1000>')

l_TimerCV.timed_wait(lock, boost::posix_time::milliseconds(wait * 1000));
                           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

PR: 227427
Reported by: antoine (via exp-run)