[$] Implicit arguments for BPF kfuncs

The kernel's "kfunc" mechanism is a way of exporting kernel functions sothat they can be called directly from BPF programs. There are over 300kfuncs in current kernels, ranging in functionality from string processing(bpf_strnlen())to custom schedulers (scx_bpf_kick_cpu())and beyond. Sometimes these kfuncs need access to context information thatis not directly available to BPF programs, and which thus cannot be passedin as arguments. The implicitarguments patch set from Ihor Solodrai is the latest attempt to solvethis problem.