Missing license and copyright statements in some file

[ghedo]

Some files are missing the usual copyright and license headers: adapters/*.h, example*.c, test.c. While it's not a serious issue, having those headers helps downstream distributors to assure correct copyright and licensing information for their packages. Would you mind adding them?

[pietern]

Tagged this for "ng". Lots of new files to add license information to.

[michael-grunder]

Closing in favor of #799