new "notifications" from UST do not strictly respect LTTNG_UST_REGISTER_TIMEOUT
We should eventually find a way to improve notifications from UST to sessiond so they don't delay .so loading (and thus application startup) when env. var. specify a LTTNG_UST_REGISTER_TIMEOUT=0. Currently, we work around this issue by setting the notification socket with a timeout of 100ms as minimum timeout if the LTTNG_UST_REGISTER_TIMEOUT value is below 100.
A cleaner fix could involve handling these notifications from a (possibly new) separate thread, and use a semaphore-based scheme to handle optional wait from the application.