Add D++ library.

vendor/DPP/include/dpp/socket.h

@@ -0,0 +1,30 @@
+#pragma once
+
+#ifndef _WIN32
+#ifndef SOCKET
+#define SOCKET int
+#endif
+#endif
+
+namespace dpp
+{
+	/**
+	 * @brief Represents a socket file descriptor.
+	 * This is used to ensure parity between windows and unix-like systems.
+	 */
+	typedef SOCKET socket;
+}
+
+#ifndef SOCKET_ERROR
+/**
+ * @brief Represents a socket in error state
+ */
+#define SOCKET_ERROR -1
+#endif
+
+#ifndef INVALID_SOCKET
+/**
+ * @brief Represents a socket which is not yet assigned
+ */
+#define INVALID_SOCKET ~0
+#endif