@smp1, @asavah: I've updated the flatbuffers package in this branch and it now compiles successfully with gcc-5.3.0 on Ubuntu 16.04, and gcc-7.3.0 on Ubuntu 17.10. Thanks to you both.
Texture Cache Maintenance Utility: Preload your texture cache for optimal UI performance. Remotely manage media libraries. Purge unused artwork to free up space. Find missing media. Configurable QA check to highlight metadata issues. Aid in diagnosis of library and cache related problems.