Use SR_SUBSCR_NO_THREAD for all subscriptions and integrate sysrepo
event pipes into a libev event loop. This eliminates approximately 30
per-subscription threads, reducing overhead on embedded ARM hardware.
A temporary poll-based "event pump" thread handles callback dispatch
during bootstrap (where sr_replace_config blocks waiting for callbacks),
then exits. After bootstrap, the single-threaded libev loop takes over
for steady-state event processing.
Note, the confd-test-mode plugin still requires use of threads so we do
not create deadlocks when calling sr_replace_config().
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
Joachim Wiberg
9e7cdf492f