Some files are physically copied from gnulib, and should get sync'ed
after each update to latest gnulib. This was forgotten during recent
updates.
* COPYING: Merge from gnulib/doc/COPYINGv3.
* tests/init.sh: Merge from gnulib/tests/init.sh.
* COPYING: Don't modify Copyright date list in imported file.
This file is one of very few exceptions in that we version-control it,
even though its primary source is another package.
Spotted by Eric Blake.