retsnoop 0.9.4:

• fix IP (instruction pointer) fetching on non-x86_64 architectures on older kernels;
• handle io_uring source code files better, after Linux code reorganization;
• automatically pick debugfs (/sys/kernel/debug/tracing) or tracefs (/sys/kernel/tracing), whichever is available;
• handle very old kernels that don't support BPF global data more gracefully.