Add missing "defined", to fix building with -Werror=undef

tinyxml2.cpp

@@ -103,7 +103,7 @@ distribution.
 #if defined(_WIN64)
 	#define TIXML_FSEEK _fseeki64
 	#define TIXML_FTELL _ftelli64
-#elif defined(__APPLE__) || defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__NetBSD__) || defined(__DragonFly__) || (__CYGWIN__)
+#elif defined(__APPLE__) || defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__NetBSD__) || defined(__DragonFly__) || defined(__CYGWIN__)
 	#define TIXML_FSEEK fseeko
 	#define TIXML_FTELL ftello
 #elif defined(__ANDROID__)