add LibreSSL.

component/libressl/buildout.cfg

+# LibreSSL is a version of the TLS/crypto stack forked from OpenSSL in
+# 2014, with goals of modernizing the codebase, improving security,
+# and applying best practice development processes.
+# http://www.libressl.org/
+
+[buildout]
+extends =
+  ../ca-certificates/buildout.cfg
+  ../coreutils/buildout.cfg
+
+parts =
+  openssl-output
+
+[libressl]
+recipe = slapos.recipe.cmmi
+url = http://ftp.openbsd.org/pub/OpenBSD/LibreSSL/libressl-2.2.3.tar.gz
+md5sum = 9a3c3c9a1c0bd6fb2659ca003de3f725
+configure-options =
+  --disable-static
+post-install =
+  rm -f ${buildout:parts-directory}/${:_buildout_section_name_}/etc/ssl/certs/* && for i in ${ca-certificates:location}/certs/*/*.crt; do ln -sv $i ${buildout:parts-directory}/${:_buildout_section_name_}/etc/ssl/certs/`${buildout:parts-directory}/${:_buildout_section_name_}/bin/openssl x509 -hash -noout -in $i`.0; done
+
+[openssl-output]
+# Shared binary location to ease migration
+recipe = plone.recipe.command
+stop-on-error = true
+update-command = ${:command}
+command = ${coreutils-output:test} -x ${:openssl}
+openssl = ${libressl:location}/bin/openssl