GitLab

Github offers the `git archive` output of each tag as a
"release tarball", bypassing the `make dist` process and
confusing people who find those download artifacts. Better
to at least offer the official releases alongside those.

This doesn't work in a normal shell, but enables 'make -C mingw'
which is convenient.

Thanks to ron for the suggestion.

These may not be final since the mingw build wasn't successful
but includes updates from following the process today.

Have successfully automated the build, but packaging
is still manual.

ftp.mozilla.org is now s3-backed archive.mozilla.org.
Old urls should redirect.

Finally managed to cross-compile a shared version of openssl
so I can use the autotools opusfile build.

Add the step to the release procedure.

This is, as far as I can remember, the process I went through
to produce the 0.1 source and win32 binary packages.

I also added a few things I wish I'd done, like stripping
the binaries and including release notes and dependency versions
in the README to help us remember next time.