Clean up a couple of warnings on Win64. The downcast of the strlen size_t
return value to int is safe here because in each case it previouls checked that
there will be no overflow.
diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 6c2c3c7..b9222b6 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -430,7 +430,7 @@
 					    NULL))
 			return NULL;
 		s = s_buffer;
-		len = strlen(s);
+		len = (int)strlen(s);
 	}
 	else if (PyObject_AsCharBuffer(v, &s, &len)) {
 		PyErr_SetString(PyExc_TypeError,