fix: fix tests build on Windows

Author: Mishura4

include/dpp/http_server.h

@@ -34,7 +34,7 @@ namespace dpp {
  * plaintext or SSL incoming request, and passes that request to a callback
  * to generate the response.
  */
-struct http_server : public socket_listener<http_server_request> {
+struct DPP_EXPORT http_server : public socket_listener<http_server_request> {
 
 	/**
 	 * @brief Request handler callback to use for all incoming HTTP(S) requests

include/dpp/socket.h

@@ -190,5 +190,7 @@ struct DPP_EXPORT raii_socket {
 	~raii_socket();
 };
 
+extern template DPP_EXPORT bool raii_socket::set_option<int>(int level, int name, int value);
+
 
 }

include/dpp/ssl_context.h

@@ -39,14 +39,14 @@ struct wrapped_ssl_ctx;
  * @param public_key Public key PEM pathname for server contexts
  * @return wrapped SSL context
  */
-wrapped_ssl_ctx* generate_ssl_context(uint16_t port = 0, const std::string &private_key = "", const std::string &public_key = "");
+DPP_EXPORT wrapped_ssl_ctx* generate_ssl_context(uint16_t port = 0, const std::string &private_key = "", const std::string &public_key = "");
 
 /**
  * @brief Release an SSL context
  * @warning Only do this if you are certain no SSL connections remain that use this context.
  * As OpenSSL is a C library it is impossible for us to track this on its behalf. Be careful!
  * @param port port number to release
  */
-void release_ssl_context(uint16_t port = 0);
+DPP_EXPORT void release_ssl_context(uint16_t port = 0);
 
 };