optimize: lower kernel version requirement from 5.6 to 5.2

pkg/ebpf_internal/internal/unix/doc.go

@@ -0,0 +1,13 @@
+// Copied from https://github.com/cilium/ebpf/tree/v0.10.0/internal/unix
+
+// Package unix re-exports Linux specific parts of golang.org/x/sys/unix.
+//
+// It avoids breaking compilation on other OS by providing stubs as follows:
+//   - Invoking a function always returns an error.
+//   - Errnos have distinct, non-zero values.
+//   - Constants have distinct but meaningless values.
+//   - Types use the same names for members, but may or may not follow the
+//     Linux layout.
+package unix
+
+// Note: please don't add any custom API to this package. Use internal/sys instead.