This updates all source files to use a new standard header for copyright
and license declaration. Notably, copyright no longer includes a date,
and we now use the standard SPDX-License-Identifier header.
This commit was done almost entirely mechanically with perl, and then
some minimal manual fixes.
Updates #6865
Signed-off-by: Will Norris <will@tailscale.com>
Sets up new file for separate silent disco goroutine, tentatively named
pathfinder for now.
Updates #540
Co-authored-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Signed-off-by: Jenny Zhang <jz@tailscale.com>
Will Norris