*zsh* no longer hangs when receiving a signal while processing a job exit
Previously, signal handlers were enabled while processing a job exit in *zsh*. Consequently, if a signal was received while using the memory allocator and its handler attempted to allocate or free memory, the *zsh* process ended up in a deadlock and became unresponsive. With this update, signal handlers are no longer enabled while processing a job exit. Instead, signals are queued for delayed execution of the signal handlers. As a result, the deadlock no longer occurs and *zsh* no longer hangs.