libalias: Remove unused function LibAliasCheckNewLink

[donner]

Summary

The functionality to detect a newly created link after processing a
single packet is decoupled from the packet processing. Every new
packet is processed asynchronously and wil reset the indicator, hence
the function is unusable. I made a Google search for third party code,
which uses the function, and failed to find one.

That's why the function should be removed: It unusable and unused.

Test Plan

Recompile without errors.

[kp]

struct libalias is exposed to userspace, right? It looks like nothing in userspace uses it. Or at least in the base system. I don't know if there are ports that care about this.

Edit: It appears you've searched and not found any.
It may be useful to at least have a comment next to the field to indicate it's unused. Ideally it should just be removed, but that'll result in ABI changes, so it makes sense to keep it.

[donner]

• Reestablish ABI without providing any functionality.
• Remove the last piece from the internal structure.

[donner]

In D30275#680105, @kp wrote:

struct libalias is exposed to userspace, right?

No. It's an opaque type, which is instantiated by library functions.

It may be useful to at least have a comment next to the field to indicate it's unused.
Ideally it should just be removed, but that'll result in ABI changes, so it makes sense to keep it.

Done, keep the ABI function call at least for anything up to 13.

[bcr]

OK from manpages.