Description:
------------
I've read the code at version 3.0.4.
I found that the expiration time is incorrectly assigned by value.

Though with the recent stable memcached (1.4.4), deleting
with expiration time seems not longer supported.
Memcached 1.4.4 will reject any delete command with
expiration.
With memcached 1.4.4, I think this patch is still need
to be applyed. Without this patch, value will never be deleted even when
I didn't assign positive expiration. Cause the original
version will always assign 1 as the expiration.

Thank you ^^



Reproduce code:
---------------
TEST CODE (with Memcached 1.4.4):
$memd = new Memcache;
$memd->connect("127.0.0.1", 11211);
$memd->set("test", "123");
$memd->delete("test");
$memd->connect("127.0.0.1", 11211);
echo $memd->get("test");
// I connect the cache server twice,
// forcing the client to get the data from server again.

PATCH:
--- memcache.c.old      2010-06-12 11:31:55.000000000 +0800
+++ memcache.c  2010-06-12 11:28:06.000000000 +0800
@@ -642,7 +642,7 @@
                        }

                        if (deleted) {
-                               pool->protocol->delete(request, request->key, request->key_len, value);
+                               pool->protocol->delete(request, request->key, request->key_len, exptime);
                        }
                        else {
                                pool->protocol->mutate(request, *key, request->key, request->key_len, invert ? -value : value, defval, defval_used, exptime);
@@ -676,7 +676,7 @@
                }

                if (deleted) {
-                       pool->protocol->delete(request, request->key, request->key_len, value);
+                       pool->protocol->delete(request, request->key, request->key_len, exptime);
                }
                else {
                        pool->protocol->mutate(request, keys, request->key, request->key_len, invert ? -value : value, defval, defval_used, exptime);


Expected result:
----------------
(empty)

Actual result:
--------------
123