Fixes in struct and socket from merge reviews.

- Following Guido's comments, renamed

  * pack_to -> pack_into
  * recv_buf -> recv_into
  * recvfrom_buf -> recvfrom_into

- Made fixes to _struct.c according to Neal Norwitz comments on the checkins
  list.

- Converted some ints into the appropriate -- I hope -- ssize_t and size_t.
diff --git a/Lib/socket.py b/Lib/socket.py
index cc5e65e..fa0e663 100644
--- a/Lib/socket.py
+++ b/Lib/socket.py
@@ -141,7 +141,7 @@
     __doc__ = _realsocket.__doc__
 
     __slots__ = ["_sock",
-                 "recv", "recv_buf", "recvfrom_buf",
+                 "recv", "recv_into", "recvfrom_into",
                  "send", "sendto", "recvfrom",
                  "__weakref__"]
 
@@ -151,10 +151,10 @@
         self._sock = _sock
         self.send = self._sock.send
         self.recv = self._sock.recv
-        self.recv_buf = self._sock.recv_buf
+        self.recv_into = self._sock.recv_into
         self.sendto = self._sock.sendto
         self.recvfrom = self._sock.recvfrom
-        self.recvfrom_buf = self._sock.recvfrom_buf
+        self.recvfrom_into = self._sock.recvfrom_into
 
     def close(self):
         self._sock = _closedsocket()