evdns: disable probing with EVDNS_BASE_DISABLE_WHEN_INACTIVE

When user install EVDNS_BASE_DISABLE_WHEN_INACTIVE flag for evdns base,
we must remove the timer that is used for probing, if current dns server
failed, otherwise it won't break the loop.
evdns: add regress for EVDNS_BASE_DISABLE_WHEN_INACTIVE base flag
evdns: add regress test for flag EVDNS_BASE_DISABLE_WHEN_INACTIVE without ns
evdns: we don't need to add retry timer in transmit_to it will be done on fail
regress dns: drop alarm() (since windows don't have it)
updates in cmake build
Merge pull request #167 from snikulov/pr_libevent_cmake_upd

updates in cmake build
Merge pull request #129 from azat/disable-probing-with-disable-when-inactive-v2

evdns: disable probing with EVDNS_BASE_DISABLE_WHEN_INACTIVE
Merge pull request #128 from azat/tests-disable-when-inactive-v5

Some tests for EVDNS_BASE_DISABLE_WHEN_INACTIVE flag
use correct tt macro for pointer compare