message: Remove OpenSSL headers from SSL transport test
diff: #include "caf/net/ssl/context.hpp"
  #include "caf/net/stream_socket.hpp"
  -CAF_PUSH_WARNINGS
  -#include <openssl/err.h>
  -#include <openssl/ssl.h>
  -CAF_POP_WARNINGS
  -
  using namespace caf;
  using namespace caf::net;
  @@ -187,15 +182,15 @@ void dummy_tls_client(stream_socket fd) {
  BEGIN_FIXTURE_SCOPE(fixture)
  -SCENARIO("openssl::async_connect performs the client handshake") {
  +SCENARIO("ssl::transport::make_client performs the client handshake") {
  GIVEN("a connection to a TLS server") {
  auto [server_fd, client_fd] = no_sigpipe(unbox(make_stream_socket_pair()));
  if (auto err = net::nonblocking(client_fd, true))
  FAIL("net::nonblocking failed: " << err);
  std::thread server{dummy_tls_server, server_fd, cert_1_pem_path,
  key_1_pem_path};
  - WHEN("connecting as a client to an OpenSSL server") {
  - THEN("openssl::async_connect transparently calls SSL_connect") {
  + WHEN("connecting as a client to an SSL server") {
  + THEN("CAF transparently calls SSL_connect") {
  net::multiplexer mpx{nullptr};
  mpx.set_thread_id();
  auto ctx = unbox(ssl::context::make_client(ssl::tls::any));
  @@ -225,14 +220,14 @@ SCENARIO("openssl::async_connect performs the client handshake") {
  }
  }
  -SCENARIO("openssl::async_accept performs the server handshake") {
  +SCENARIO("ssl::transport::make_server performs the server handshake") {
  GIVEN("a socket that is connected to a client") {
  auto [server_fd, client_fd] = no_sigpipe(unbox(make_stream_socket_pair()));
  if (auto err = net::nonblocking(server_fd, true))
  FAIL("net::nonblocking failed: " << err);
  std::thread client{dummy_tls_client, client_fd};
  - WHEN("acting as the OpenSSL server") {
  - THEN("openssl::async_accept transparently calls SSL_accept") {
  + WHEN("acting as the SSL server") {
  + THEN("CAF transparently calls SSL_accept") {
  net::multiplexer mpx{nullptr};
  mpx.set_thread_id();
  auto ctx = unbox(ssl::context::make_server(ssl::tls::any));
  