Revert "appease IWYU again"

This reverts commit 39f2cea.

Author: Blueflowerss

src/mapbuffer.cpp

@@ -19,6 +19,7 @@
 #include "debug.h"
 #include "filesystem.h"
 #include "flexbuffer_json.h"
+#include "game.h"
 #include "input.h"
 #include "json.h"
 #include "json_loader.h"
@@ -39,6 +40,9 @@
 
 #define dbg(x) DebugLog((x),D_MAP) << __FILE__ << ":" << __LINE__ << ": "
 
+// NOLINTNEXTLINE(cata-static-declarations)
+extern const int savegame_version;
+
 static std::string quad_file_name( const tripoint_abs_omt &om_addr )
 {
     return string_format( "%d.%d.%d.map", om_addr.x(), om_addr.y(), om_addr.z() );