Since around 2018, we have been using spaces for indentation for newly
added code[1]. The mixed use of tabs and spaces has repeatedly confused
new contributors who configured their editors to use a different tab
size than 8. Since git blame can now skip specific commits, ruby/ruby
did a mass reformatting of tabs in 2022[2]. Do the same in ruby/openssl.

While at it, fix a few indentation issues, mainly in switch-case labels
and in ossl_ssl_session.c, which used doubled indentation size.

This patch contains white-space changes only. git diff -w output should
be empty.

[1] https://bugs.ruby-lang.org/issues/14246
[2] https://bugs.ruby-lang.org/issues/18891

https://github.com/ruby/openssl/commit/4d6214f507

These declarations were added to every source file because older
versions of RDoc did not resolve ancestor tree across files. Since
RDoc 6.9.0 supports this, this workaround is no longer needed.

    https://redirect.github.com/ruby/rdoc/pull/1217

https://github.com/ruby/openssl/commit/6491ce63be

With the introduction of OpenSSL 3 providers, newly implemented
algorithms do not necessarily have a corresponding NID assigned. To use
such an algorithm, it has to be "fetched" from providers using the new
EVP_*_fetch() functions.

For digest algorithms, we have to use EVP_MD_fetch() instead of the
existing EVP_get_digestbyname(). However, it is not a drop-in
replacement because:

 - EVP_MD_fetch() does not support all algorithm name aliases recognized
   by EVP_get_digestbyname().

 - Both return an EVP_MD, but the one returned by EVP_MD_fetch() is
   sometimes reference counted and the user has to explicitly release
   it with EVP_MD_free().

So, keep using EVP_get_digestbyname() for all OpenSSL versions for now,
and fall back to EVP_MD_fetch() if it fails. In the latter case, prepare
a T_DATA object to manage the fetched EVP_MD's lifetime.

https://github.com/ruby/openssl/commit/9fc2179403

Drop support for OpenSSL 1.0.2. It has reached upstream EOL in 2019-12.

Most distributions that shipped with OpenSSL 1.0.2 have also reached
EOL, or provide a newer version in the package repository:

 - RHEL 7 (EOL 2024-06)
 - Ubuntu 16.04 LTS (EOL 2021-04)
 - Amazon Linux 2 (EOL 2026-06, but OpenSSL 1.1.1 can be installed via
   the openssl11{,-devel} package)

https://github.com/ruby/openssl/commit/38ec6fd50e

Drop support for LibreSSL 3.1-3.8. LibreSSL 3.8 has reached its EOL in
2024-10.

https://github.com/ruby/openssl/commit/f33d611f9f

We use the following site for that now:

* https://tools.ietf.org/ or http
* https://datatracker.ietf.org or http

Today, IETF said the official site of RFC is www.rfc-editor.org.

FYI: https://authors.ietf.org/en/references-in-rfcxml

I replaced them to www.rfc-editor.org.

Let's consistently use the word "password". Although they are considered
synonymous, the mixed usage in the rdoc can cause confusion.

OpenSSL::KDF.scrypt is an exception. This is because RFC 7914 refers to
the input parameter as "passphrase".

https://github.com/ruby/openssl/commit/06d67640e9

LibreSSL 3.6 added support for HKDF in EVP. Enable this in ossl_kdf.c.

https://github.com/ruby/openssl/commit/9bdd39a7e2

The values from RFC 5869
https://datatracker.ietf.org/doc/html/rfc5869#appendix-A.1

https://github.com/ruby/openssl/commit/ec14a87f4f

https://github.com/ruby/openssl/commit/b28fb2f05c