reduce LibreSSL warnings

* ext/openssl/extconf.rb: LibreSSL headers emit "overriding WinCrypt
  defines" warnings if wincrypt.h has been included (except for
  x509.h) on Windows.  get rid of including the header by defining
  NOCRYPT macro.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64101 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/openssl/extconf.rb

@@ -114,6 +114,10 @@ engines.each { |name|
   OpenSSL.check_func_or_macro("ENGINE_load_#{name}", "openssl/engine.h")
 }
 
+if ($mswin || $mingw) && have_macro("LIBRESSL_VERSION_NUMBER")
+  $defs.push("-DNOCRYPT")
+end
+
 # added in 1.0.2
 have_func("EC_curve_nist2nid")
 have_func("X509_REVOKED_dup")