Fix potential leak in request_set_header

request_set_header doesn't change the request if the header value is
NULL.  The current implementation allows a leak if someone tried to do
something like:

request_set_header (req, aprintf("%sConnection", proxy?"Proxy-":""),
                    value, rel_name);

If VALUE is NULL, the name will not be released.  No code in Wget does
this now, but in the future it well may.  This patch fixes the bug:

2005-04-17  Hrvoje Niksic  <[email protected]>

	* http.c (request_set_header): Free NAME when VALUE is NULL and
	freeing the header name is requested.

Index: src/http.c
===================================================================
RCS file: /pack/anoncvs/wget/src/http.c,v
retrieving revision 1.159
diff -u -r1.159 http.c
--- src/http.c	2005/04/16 13:06:29	1.159
+++ src/http.c	2005/04/17 16:57:21
@@ -234,7 +234,13 @@
   struct request_header *hdr;
   int i;
   if (!value)
-    return;
+    {
+      /* A NULL value is a no-op; if freeing the name is requested,
+	 free it now to avoid leaks.  */
+      if (release_policy == rel_name || release_policy == rel_both)
+	xfree (name);
+      return;
+    }
   for (i = 0; i < req->hcount; i++)
     {
       hdr = &req->headers[i];