Change int to Py_ssize_t in several places.
Add (int) casts to silence compiler warnings.
Raise Python exceptions for overflows.
diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 409afd8..c9da78c 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -2514,7 +2514,7 @@
 filterunicode(PyObject *func, PyObject *strobj)
 {
 	PyObject *result;
-	register int i, j;
+	register Py_ssize_t i, j;
 	Py_ssize_t len = PyUnicode_GetSize(strobj);
 	Py_ssize_t outlen = len;