Fix clang tidy include error

Author: ChillerDragon

src/server/ddnet_callback_ctx.cpp

@@ -1,5 +1,6 @@
 #include <twbl/teeworlds/character.h>
 #include <twbl/teeworlds/gamecontext.h>
+#include <twbl/teeworlds/protocol.h>
 
 #include "ddnet_callback_ctx.h"
 

src/twbl/teeworlds/protocol.h

@@ -1,6 +1,15 @@
 #ifndef TWBL_SRC_TWBL_PROTOCOL_H
 #define TWBL_SRC_TWBL_PROTOCOL_H
 
+#if __has_include(<engine/shared/protocol.h>)
+#include <engine/shared/protocol.h>
+#else
+enum
+{
+	MAX_CLIENTS = 128,
+};
+#endif
+
 #if __has_include(<game/generated/protocol.h>)
 #include <game/generated/protocol.h>
 #else
@@ -21,6 +30,11 @@ enum
 	NUM_WEAPONS
 };
 
+enum
+{
+	WEAPON_SELF = -2,
+};
+
 enum
 {
 	EMOTICON_OOP,