Clear the reference counter in WSACleanup, with regression test.

dlls/winsock/socket.c

@@ -831,8 +831,10 @@ int WINAPI WSAStartup(WORD wVersionRequested, LPWSADATA lpWSAData)
  */
 INT WINAPI WSACleanup(void)
 {
-    if (num_startup)
+    if (num_startup) {
+        num_startup--;
         return 0;
+    }
     SetLastError(WSANOTINITIALISED);
     return SOCKET_ERROR;
 }

dlls/winsock/tests/sock.c

@@ -709,8 +709,15 @@ static void Init (void)
 
 static void Exit (void)
 {
+    INT ret, err;
     TlsFree ( tls );
-    ok ( WSACleanup() == 0, "WSACleanup failed\n" );
+    ret = WSACleanup();
+    err = WSAGetLastError();
+    ok ( ret == 0, "WSACleanup failed ret = %d GetLastError is %d\n", ret, err);
+    ret = WSACleanup();
+    err = WSAGetLastError();
+    ok ( ret == SOCKET_ERROR && err ==  WSANOTINITIALISED,
+            "WSACleanup returned %d GetLastError is %d\n", ret, err);
 }
 
 static void StartServer (LPTHREAD_START_ROUTINE routine,