Test opened file descriptor

Test the already opened file descriptor rather than opening it again as
a test.

(cherry picked from commit b6642ed1ce65749e3fcc6f6c7853b96a0ba2fd97)
Update GPL boilerplate

The mailing address for the Free Software Foundation was incorrect in
the GPL boilerplate.

Thanks Walter Fey, DL8FCL for reporting this issue.

(cherry picked from commit b74efdd52ad30693c9513537f4f8c93d0f5235ff)
Advance to 2.5.0~rc2