Valgrind fork+execs debuginfod-find in order to perform debuginfod
queries. Any SIGCHLD debuginfod-find sends upon termination can
mistakenly be delivered to the client running under valgrind.
To prevent this, record in a hash table the PID of each process
valgrind forks for internal use. Do not send SIGCHLD to the client
if it is from a PID in this hash table.
https://bugs.kde.org/show_bug.cgi?id=445011