When I updated to Stretch from Jessie the picam application on my RPi stopped working because it couldn't find the libraries mentioned above. I tried sym linking and making copies of the corresponding brcm libraries so no avail. ldconfig was not impressed
By chance I decided to run sudo rpi-update this morning: I had updated the OS, so maybe I should update the firmware too. The missing libraries are now back in /opt/vc/lib. They have last modified dates of 22:49 on August 23rd. picam is now working again.
Posted in case there are other users and applications affected by the apparent loss of these libraries.