When compiled with OpenSSL <= 1.1.1, OpenSSL::SSL::SSLContext#setup
does not raise an exception on an error return from
SSL_CTX_load_verify_locations(), but instead only prints a verbose-mode
warning. This is not helpful since it very likely indicates an actual
error, such as the specified file not being readable.

Also, OpenSSL's error queue is not correctly cleared:

	$ ruby -w -ropenssl -e'OpenSSL.debug=true; ctx=OpenSSL::SSL::SSLContext.new; ctx.ca_file="bad-path"; ctx.setup; pp OpenSSL.errors'
	-e:1: warning: can't set verify locations
	["error:02001002:system library:fopen:No such file or directory",
	 "error:2006D080:BIO routines:BIO_new_file:no such file",
	 "error:0B084002:x509 certificate routines:X509_load_cert_crl_file: system lib"]

The behavior is currently different when compiled with OpenSSL >= 3.0:
SSLError is raised if SSL_CTX_load_verify_file() or
SSL_CTX_load_verify_dir() fails.

This inconsistency was unintentionally introduced by commit https://github.com/ruby/openssl/commit/5375a55ffc35
("ssl: use SSL_CTX_load_verify_{file,dir}() if available", 2020-02-22).
However, raising SSLError seems more appropriate in this situation.
Let's adjust the OpenSSL <= 1.1.1 code so that it behaves the same way
as the OpenSSL >= 3.0 code currently does.

Fixes: https://github.com/ruby/openssl/issues/649

https://github.com/ruby/openssl/commit/7eb10f7b75

This reverts commit https://github.com/ruby/openssl/commit/fc4629d246f2.

The test case "test_connect_certificate_verify_failed_exception_message"
does want to check the reason behind a certificate verification failure
to be included in the exception message.

https://github.com/ruby/openssl/commit/c309745eb8

A tentative measures fo https://github.com/ruby/openssl/issues/606.

With OpenSSL 3.1.0, the error message at connection using "self-signed
certificate" seems to return `SSL_R_TLSV1_ALERT_UNKNOWN_CA` instead of
`SSL_R_CERTIFICATE_VERIFY_FAILED`.

https://github.com/ruby/openssl/commit/fc4629d246

https://github.com/ruby/openssl/commit/a3d230d4e0

As noted in commit https://github.com/ruby/openssl/commit/a2ed156cc9f1 ("test/test_ssl: do not run NPN tests
for LibreSSL >= 2.6.1", 2017-08-13), NPN is known not to work properly
on LibreSSL.

Disable NPN support on LibreSSL, whether OPENSSL_NO_NEXTPROTONEG is
defined or not.

NPN is less relevant today anyway. Let's also silence test suite when
it's not available.

https://github.com/ruby/openssl/commit/289f6e0e1f

- This callback is invoked when TLS key material is generated or
  received, in order to allow applications to store this keying material
  for debugging purposes.
- It is invoked with an `SSLSocket` and a string containing the key
  material in the format used by NSS for its SSLKEYLOGFILE debugging
  output.
- This commit adds the Ruby binding `keylog_cb` and the related tests
- It is only compatible with OpenSSL >= 1.1.1. Even if LibreSSL implements
  `SSL_CTX_set_keylog_callback()` from v3.4.2, it does nothing (see
  https://github.com/libressl-portable/openbsd/commit/648d39f0f035835d0653342d139883b9661e9cb6)

https://github.com/ruby/openssl/commit/3b63232cf1

Add OpenSSL::SSL::SSLSocket#export_keying_material to support RFC 5705

https://github.com/ruby/openssl/commit/65530b887e

It does not raise an error when setting an invalid value to SSLContext
ciphers on Ubuntu 18.04.

https://github.com/ruby/openssl/commit/8c96a69b0d

https://github.com/ruby/openssl/commit/862d92de93

LibreSSL 3.5 switched the cipher naming to match OpenSSL.

https://github.com/ruby/openssl/commit/bf198278bd