This was only used by the i?86-pc-linux-gnu target which we've removed,
and even though it's using a "sys/linux/" dir to make it sound like it
only depends on the Linux kernel, it's actually tied to glibc APIs built
on top of Linux. Since the code relies on internal glibc APIs and has
been broken for some time, punt it all. If someone wants to bring it
back, they can try and actually keep the Linux-vs-glibc APIs separate.
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