ifnet: Integrate if_unroute() into if_down()

[zlei]

Summary

if_unroute() is static since 2004 and is not used anywhere except for
if_down().

This also makes it easier to grep by the pattern if_flags &= ~IFF_UP.

No functional change intended.

MFC after: 1 week

[glebius]

Thanks!

I have only light concerns with aggressive MFC plan on refactoring changes. Sometimes bugs sneak into refactorings that seems to be innocent. Whether to MFC or not is almost always is up to decision of merging committer. My personal take is that I would MFC refactoring changes only if they are a prerequisite for a following bugfix or a new driver/module that goes to a stable branch.

[zlei]

In D49356#1125613, @glebius wrote:

Thanks!

I have only light concerns with aggressive MFC plan on refactoring changes. Sometimes bugs sneak into refactorings that seems to be innocent.

Yeah, I think I have checked that carefully. For this case, I checked the usage of if_unroute() from -current to stable/8.

Whether to MFC or not is almost always is up to decision of merging committer. My personal take is that I would MFC refactoring changes only if they are a prerequisite for a following bugfix or a new driver/module that goes to a stable branch.

Valid point. Well I tend to MFC if possible, mainly to reduce the drift between stable branches, and it is easier to filter out critical changes between branches.

Anyway I'll do that carefully.