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.
- Those are not used any where
- Those are not supported by the sse/neon accelerated versions
- And I see very little use cases for those.
Signed-off-by: Sylvain Munaut <tnt@246tNt.com>