It does nothing and never did and I don't think anybody remembers what
the original goal for it was.
Updates #5229 (fixes, but need to clean it up in another repo too)
Change-Id: I81cc6ff44d6d2888bc43e9145437f4c407907ea6
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
They were scattered/duplicated in misc places before.
It can't be in the client package itself for circular dep reasons.
This new package is basically tailcfg but for localhost
communications, instead of to control.
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>