use-after-free at flow shutdown
Instructions to reproduce:
Build librist with asan
SHELL-1 $ ./tools/ristreceiver -i rist://@127.0.0.1:4754 -o udp://127.0.0.1:8010 -v 9 |& tee recv.log
SHELL-2 $ ./tools/ristsender -o rist://127.0.0.1:4754 -i udp://@127.0.0.1:8000 -v 9
SHELL-3 $ ffmpeg -f lavfi -re -i testsrc=r=25 -vf format=yuv420p -c:v libx264 -tune:v zerolatency -f mpegts -pkt_size '188*7' udp://127.0.0.1:8000
wait 30 seconds
SHELL-3 ctrl-C
SHELL-2 ctrl-C
SHELL-1 wait for asan to crash the program