Add zlib to libs when finding openssl (RIPD-1496):

if openssl is configured with compression support AND you link
to the static lib, you are going to need to link to zlib.

Fundamentally the CMake finder should take care of this (as
described in https://gitlab.kitware.com/cmake/cmake/issues/16885),
but we work around it here by adding zlib explicitly. Update
beast error test for OpenSSL 1.1.0

src/test/beast/beast_asio_error_test.cpp

@@ -33,7 +33,12 @@ public:
                 boost::system::error_code (335544539,
                     boost::asio::error::get_ssl_category ());
             std::string const s = beast::error_message_with_ssl(ec);
+
+#ifdef SSL_R_SHORT_READ
             BEAST_EXPECT(s == " (20,0,219) error:140000DB:SSL routines:SSL routines:short read");
+#else
+            BEAST_EXPECT(s == " (20,0,219) error:140000DB:SSL routines:SSL routines:reason(219)");
+#endif
         }
     }
 };