[$] Verifier-state pruning in BPF

The BPF verifier works, on a theoretical level, by considering every possiblepath that a BPF program could take. As a practical matter, however, it needs todo that in a reasonable amount of time. At the2025 Linux Plumbers Conference, Mahe Tardy and Paul Chaignongave a detailed explanation(slides;video) ofthe main mechanism that it uses to accomplish that: state pruning. They focusedon two optimizations that help reduce the number of paths the verifier needs tocheck, and discussed some of the complications the optimizations introduced to the verifier'scode.