Issue #15989: Fix several occurrences of integer overflow
when result of PyLong_AsLong() narrowed to int without checks.

This is a backport of changesets 13e2e44db99d and 525407d89277.
diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index 4f896fd..bc3372f 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -1737,7 +1737,7 @@
 static PyObject *
 sock_setblocking(PySocketSockObject *s, PyObject *arg)
 {
-    int block;
+    long block;
 
     block = PyLong_AsLong(arg);
     if (block == -1 && PyErr_Occurred())
@@ -2219,7 +2219,7 @@
     int backlog;
     int res;
 
-    backlog = PyLong_AsLong(arg);
+    backlog = _PyLong_AsInt(arg);
     if (backlog == -1 && PyErr_Occurred())
         return NULL;
     Py_BEGIN_ALLOW_THREADS
@@ -2822,7 +2822,7 @@
     int how;
     int res;
 
-    how = PyLong_AsLong(arg);
+    how = _PyLong_AsInt(arg);
     if (how == -1 && PyErr_Occurred())
         return NULL;
     Py_BEGIN_ALLOW_THREADS