In once case there was a direct call to `free()` even though a mempool is used. In other cases the code called the context structure functions instead of the generic ones.

See merge request !536

This reverts commit 920f9b0f.

* code refactor for semantic checks
* stand-alone tool for semantic check (kzonecheck)

MR !510

Coverity detected a data race condition.

This reverts merge request !532

This reverts merge request !532

events: fix the race condition while avoiding a deadlock

Add a conditional variable to wait for an event to finish running within
evsched to avoid race condition (memory deallocating) and a potential
deadlock (with evsched). This solution continues in enabling access to
the evsched heap during event callback execution to avoid possible soft
lockup.