Added the const qualifier to char* variables that refer to readonly internal
UTF-8 represenatation of Unicode objects.
diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index c760522..2b43fd8 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -305,7 +305,7 @@
             "could not acquire lock for %A at interpreter "
             "shutdown, possibly due to daemon threads",
             (PyObject *) self);
-        char *msg = PyUnicode_AsUTF8(msgobj);
+        const char *msg = PyUnicode_AsUTF8(msgobj);
         Py_FatalError(msg);
     }
     return 1;