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/struct.py b/Lib/struct.py
index 51ee29a..9113e71 100644
--- a/Lib/struct.py
+++ b/Lib/struct.py
@@ -62,7 +62,7 @@
         o = _compile(fmt)
     return o.pack(*args)
 
-def pack_to(fmt, buf, offset, *args):
+def pack_into(fmt, buf, offset, *args):
     """
     Pack the values v2, v2, ... according to fmt, write
     the packed bytes into the writable buffer buf starting at offset.
@@ -72,7 +72,7 @@
         o = _cache[fmt]
     except KeyError:
         o = _compile(fmt)
-    return o.pack_to(buf, offset, *args)
+    return o.pack_into(buf, offset, *args)
 
 def unpack(fmt, s):
     """