[$] An update on GCC BPF support

Jose Marchesi and David Faust kicked off the BPF track at the 2025 Linux Storage,Filesystem, Memory-Management, and BPF Summit with an extra-long session on whatthey have been doing to support compiling to BPF in GCC. Overall, the project is slowly workingtoward full support for BPF, with most of the self-tests now passing usingFaust's in-progress patches. However, the progress toward that goal has turned upa number of problems with how Clang supports BPF that needed to be discussed atlength to find a path forward for both projects.