Drop support for LibreSSL 2.4

LibreSSL 2.4 reached its EOL in 2017-09.

Author: rhenium

.travis.yml

@@ -21,7 +21,6 @@ matrix:
     - env: RUBY_VERSION=ruby-2.4 OPENSSL_VERSION=openssl-1.0.1
     - env: RUBY_VERSION=ruby-2.4 OPENSSL_VERSION=openssl-1.0.2
     - env: RUBY_VERSION=ruby-2.4 OPENSSL_VERSION=openssl-1.1.0
-    - env: RUBY_VERSION=ruby-2.4 OPENSSL_VERSION=libressl-2.4
     - env: RUBY_VERSION=ruby-2.4 OPENSSL_VERSION=libressl-2.5
     - env: RUBY_VERSION=ruby-2.4 OPENSSL_VERSION=libressl-2.6
     - language: ruby

test/test_ocsp.rb

@@ -122,12 +122,12 @@ def test_request_sign_verify
 
     assert_equal true, req.verify([@cert], store, OpenSSL::OCSP::NOINTERN)
     ret = req.verify([@cert], store)
-    if ret || openssl?(1, 0, 2) || libressl?(2, 4, 2)
+    if ret || openssl?(1, 0, 2)
       assert_equal true, ret
     else
       # RT2560; OCSP_request_verify() does not find signer cert from 'certs' when
       # OCSP_NOINTERN is not specified.
-      # fixed by OpenSSL 1.0.1j, 1.0.2 and LibreSSL 2.4.2
+      # fixed by OpenSSL 1.0.1j, 1.0.2
       pend "RT2560: ocsp_req_find_signer"
     end
 
@@ -262,11 +262,6 @@ def test_single_response_check_validity
     bres.add_status(cid2, OpenSSL::OCSP::V_CERTSTATUS_REVOKED, OpenSSL::OCSP::REVOKED_STATUS_UNSPECIFIED, -400, -300, nil, [])
     bres.add_status(cid2, OpenSSL::OCSP::V_CERTSTATUS_GOOD, nil, nil, Time.now + 100, nil, nil)
 
-    if bres.responses[2].check_validity # thisUpdate is in future; must fail
-      # LibreSSL bug; skip for now
-      pend "OCSP_check_validity() is broken"
-    end
-
     single1 = bres.responses[0]
     assert_equal false, single1.check_validity
     assert_equal false, single1.check_validity(30)
@@ -275,6 +270,8 @@ def test_single_response_check_validity
     assert_equal true, single2.check_validity
     assert_equal true, single2.check_validity(0, 500)
     assert_equal false, single2.check_validity(0, 200)
+    single3 = bres.responses[2]
+    assert_equal false, single3.check_validity
   end
 
   def test_response