Add missing headers (#15075)

Some systems must explicitly include these headers.

3rdparty/pine/pine_server.h

@@ -27,10 +27,8 @@
 #include <sys/un.h>
 #include <arpa/inet.h>
 #include <poll.h>
-#if defined(__DragonFly__) || defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__APPLE__)
 #include <unistd.h>
 #endif
-#endif
 
 #ifdef _WIN32
 constexpr SOCKET invalid_socket = INVALID_SOCKET;