De-duplicate number of menu text bytes

I've moved this to a define that gets declared in Game.h. I could've
made it a const int, but that's only legal in C++ mode.

desktop_version/src/Game.h

@@ -14,10 +14,12 @@ namespace tinyxml2
     class XMLElement;
 }
 
+/* 40 chars (160 bytes) covers the entire screen, + 1 more for null terminator */
+#define MENU_TEXT_BYTES 161
+
 struct MenuOption
 {
-    char text[161]; // 40 chars (160 bytes) covers the entire screen, + 1 more for null terminator
-    // WARNING: should match Game::menutextbytes below
+    char text[MENU_TEXT_BYTES];
     bool active;
 };
 
@@ -252,7 +254,6 @@ public:
     int current_credits_list_index;
     int menuxoff, menuyoff;
     int menuspacing;
-    static const int menutextbytes = 161; // this is just sizeof(MenuOption::text), but doing that is non-standard
     std::vector<MenuStackFrame> menustack;
 
     void inline option(const char* text, bool active = true)