Added missing multiple header inclusion prevention definition

CHANGES

@@ -6,6 +6,10 @@
 
                                   Changelog
 
+Yang Tse (11 Jul 2008)
+- Added missing multiple header inclusion prevention definition for header
+  file content_encoding.h
+
 Daniel Fandrich (11 Jul 2008)
 - Fixed test 553 to pass the torture test.
 

lib/content_encoding.h

+#ifndef __CURL_CONTENT_ENCODING_H
+#define __CURL_CONTENT_ENCODING_H
 /***************************************************************************
  *                                  _   _ ____  _
  *  Project                     ___| | | |  _ \| |
@@ -5,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2007, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2008, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -39,3 +41,5 @@ CURLcode
 Curl_unencode_gzip_write(struct connectdata *conn,
                          struct SingleRequest *k,
                          ssize_t nread);
+
+#endif