Fix broken tests on MacOS

[0xPoe]

When I run make test on my MacOS. I got some errors:

ebpf/rlimit/internal/internal_mirror.go:13:20: undefined: unix.BPF_OBJ_NAME_LEN
ebpf/rlimit/internal/internal_mirror.go:39:36: undefined: unix.SYS_BPF
ebpf/cmd/playground/main.go:27:26: undefined: ebpfspy.NewSession
ebpf/cmd/playground/main.go:48:38: undefined: ebpfspy.SessionOptions
ebpf/cmd/playground/main.go:50:17: undefined: ebpfspy.SessionOptions
ebpf/cmd/playground/main.go:54:24: undefined: symtab.CacheOptions

This PR try add the right build tag to skip it on MacOS.

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