radv secure compile feature
This allows applications such as steam to precompile large fossilize dbs for game upfront removing in-game stuttering. Based on the number given to the env var RADV_SECURE_COMPILE_THREADS a number of processes are forked at device creation time and then have a seccomp filter installed. The parent process then passes the pipelines to be compiled to the secure process.
RADV_SECURE_COMPILE_THREADS=8 ./fossilize-replay --num-threads 8 --shader-cache-size 0 --ignore-derived-pipelines pipeline_cache.foz
TODO: Still needed are timeouts to the pipe communication so that we don't get stuck waiting forever if a process crashes etc.