Make compiling D-Star conditional.

DStarHeader.cpp

@@ -1,5 +1,5 @@
 /*
-*   Copyright (C) 2016 by Jonathan Naylor G4KLX
+*   Copyright (C) 2016,2023 by Jonathan Naylor G4KLX
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
@@ -20,6 +20,8 @@
 #include "DStarHeader.h"
 #include "CRC.h"
 
+#if defined(USE_DSTAR)
+
 #include <cstdio>
 #include <cassert>
 #include <cstring>
@@ -163,3 +165,6 @@ void CDStarHeader::get(unsigned char* header) const
 
 	CCRC::addCCITT161(header, DSTAR_HEADER_LENGTH_BYTES);
 }
+
+#endif
+