linux: add SO_DETACH_REUSEPORT_BPF

[swananan]

Description

Add SO_DETACH_REUSEPORT_BPF for Linux, following the same approach as #3917.

This exposes the constant on the Linux arch modules that define socket option values directly (generic, mips, powerpc, and sparc) and updates the Linux semver list.

SO_DETACH_REUSEPORT_BPF is already defined by musl starting in v1.2.0, but libc CI still runs old-musl jobs as well, so the libc-test constant check is still skipped for musl.

Sources

• Linux UAPI: https://github.com/torvalds/linux/blob/897d54018cc9aa97fd1529ca08a53b429d05a566/include/uapi/asm-generic/socket.h#L117-L123
• musl v1.2.0: https://github.com/ifduyue/musl/blob/v1.2.0/include/sys/socket.h#L1572-L1576

Checklist

• Relevant tests in libc-test/semver have been updated
• No placeholder or unstable values like *LAST or *MAX are
  included (see #3131)
• Tested locally (cd libc-test && cargo test --target mytarget);
  especially relevant for platforms that may not be checked in CI

[swananan]

Looks like CI is flaky, will retry this tomorrow.

[JohnTitor]

Looks good, thanks!

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