Drop support for LibreSSL < 2.3

We have changed the support policy for LibreSSL: we now support only
maintained stable branches.

Quoting from libressl.org[1]:

> LibreSSL transitions to a new stable release branch every 6 months in
> coordination with the OpenBSD development schedule. LibreSSL stable
> branches are updated for 1 year after their corresponding OpenBSD
> branch is tagged for release.

So, LibreSSL 2.2, which was shipped by OpenBSD 5.8 released on 2015-08,
is no longer supported officially by the OpenBSD team.

[1] http://www.libressl.org/releases.html

.travis.yml

@@ -21,8 +21,6 @@ matrix:
     - env: RUBY_VERSION=ruby-2.3 OPENSSL_VERSION=openssl-1.0.1 OSSL_MDEBUG=1
     - env: RUBY_VERSION=ruby-2.3 OPENSSL_VERSION=openssl-1.0.2 OSSL_MDEBUG=1
     - env: RUBY_VERSION=ruby-2.3 OPENSSL_VERSION=openssl-1.1.0 OSSL_MDEBUG=1
-    - env: RUBY_VERSION=ruby-2.3 OPENSSL_VERSION=libressl-2.1
-    - env: RUBY_VERSION=ruby-2.3 OPENSSL_VERSION=libressl-2.2
     - env: RUBY_VERSION=ruby-2.3 OPENSSL_VERSION=libressl-2.3
     - env: RUBY_VERSION=ruby-2.3 OPENSSL_VERSION=libressl-2.4
     - env: RUBY_VERSION=ruby-2.3 OPENSSL_VERSION=libressl-2.5

History.md

@@ -17,7 +17,7 @@ Supported platforms
 
 * OpenSSL 1.0.0, 1.0.1, 1.0.2, 1.1.0
 * OpenSSL < 0.9.8 is no longer supported.
-* LibreSSL 2.1, 2.2, 2.3, 2.4
+* LibreSSL 2.3, 2.4, 2.5
 * Ruby 2.3, 2.4
 
 Notable changes

tool/ruby-openssl-docker/Dockerfile

@@ -50,19 +50,7 @@ RUN curl -s https://www.openssl.org/source/openssl-1.1.0b.tar.gz | tar -C /build
       debug-linux-x86_64 && \
     make && make install_sw
 
-# Supported libressl versions: 2.1, 2.2, 2.3, 2.4, 2.5
-RUN curl -s http://ftp.openbsd.org/pub/OpenBSD/LibreSSL/libressl-2.1.10.tar.gz | tar -C /build/openssl -xzf -
-RUN cd /build/openssl/libressl-2.1.10 && \
-    ./configure \
-      --prefix=/opt/openssl/libressl-2.1 && \
-    make && make install
-
-RUN curl -s http://ftp.openbsd.org/pub/OpenBSD/LibreSSL/libressl-2.2.9.tar.gz | tar -C /build/openssl -xzf -
-RUN cd /build/openssl/libressl-2.2.9 && \
-    ./configure \
-      --prefix=/opt/openssl/libressl-2.2 && \
-    make && make install
-
+# Supported libressl versions: 2.3, 2.4, 2.5
 RUN curl -s http://ftp.openbsd.org/pub/OpenBSD/LibreSSL/libressl-2.3.8.tar.gz | tar -C /build/openssl -xzf -
 RUN cd /build/openssl/libressl-2.3.8 && \
     ./configure \