ola: fix compilation with musl 1.2.3

musl 1.2.3 defines NULL as nullptr. cannot use reinterpret_cast with
nullptr.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

ola/AutoStart.cpp

@@ -110,11 +110,11 @@ TCPSocket *ConnectToServer(unsigned short port) {
     // Try to start the server, we pass --daemon (fork into background) and
     // --syslog (log to syslog).
     execlp("olad", "olad", "--daemon", "--syslog",
-#ifdef __FreeBSD__
-           reinterpret_cast<char*>(0));
+#if __cplusplus >= 201103L
+           nullptr);
 #else
            reinterpret_cast<char*>(NULL));
-#endif  // __FreeBSD__
+#endif  // __cplusplus >= 201103L
     OLA_WARN << "Failed to exec: " << strerror(errno);
     _exit(1);
   }