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: I5050285e75cf120407a1d883e99b3c4bcae8ffd7
Using mbedtls commit f9c599cd8ac9d00c484d4f5b027e18c6af4f9fdf before
they re-licensed to Apache 2.0, so we have a GPL-v2-or-later bsae64
implementation and avoid having code under a different license in the
tree.
This code is the unmodified import, so we can record any local changes
compared to the original version.
Change-Id: I39a9d3ab98257d21b9439b00528c744efa372c14