Remove the paragraph about writing to the Free Software Foundation's
mailing address. The FSF has changed addresses in the past, and may do
so again. In 2021 this is not useful, let's rather have a bit less
boilerplate at the start of source files.
Change-Id: I8ba71ab9ccde4ba25151ecbeb2a323f706b57d43
Take the chance to update some includes using files available in that
subdir to have them ina more uniform way.
Change-Id: Ibda3c54fd4dc3f6b845cc373f1a1e6b758c1ea82