Make saveFilePath not an std::string

Since it only ever gets assigned from FILESYSTEM_getUserSaveDirectory(),
and that function returns a C string, and the variable is only ever read
from again, this doesn't need to be an std::string.

desktop_version/src/Game.h

@@ -183,7 +183,7 @@ public:
 
     void initteleportermode(void);
 
-    std::string saveFilePath;
+    const char* saveFilePath;
 
 
     int door_left;