Another linkname usage

[HeRaNO]

https://github.com/golang/go/blob/master/src/internal/poll/fd_poll_runtime.go#L165-L179 shows we use IsPollDescriptor as a linkname, and we used here https://github.com/opencontainers/runc/blob/main/libcontainer/utils/utils_unix.go#L112-L119.

So maybe we need a -ldflags=-checklinkname=0 to make the compiling stage happy on Go 1.23. Or we can make a change to avoid using linkname.

UPD: Fortunately it's added at runc 1.2.0-rc1. We can eliminate it to avoid being on the hall of shame.

[HeRaNO]

Not quite sure why the compiling stage is ok on tip... Maybe I made a mistake (is now we have a so-called Handshake situation?). Comments welcome.

[cyphar]

We are aware of this and have an upstream proposal to avoid the need for go:linkname for getting whether file descriptors are internal to the Go runtime.

(For what it's worth, I don't really care about their "hall of shame". All of our go:linkname usages are to workaround stdlib bugs or limitations of Go that make Go unusable as a "systems language" without hacks.)