fixed bug #310105 with http_proxy environments with patch provided by

* nanohttp.c: fixed bug #310105 with http_proxy environments with
  patch provided by Peter Breitenlohner
Daniel
diff --git a/nanohttp.c b/nanohttp.c
index de89ab7..def66b3 100644
--- a/nanohttp.c
+++ b/nanohttp.c
@@ -248,8 +248,10 @@
 
 void
 xmlNanoHTTPCleanup(void) {
-    if (proxy != NULL)
+    if (proxy != NULL) {
 	xmlFree(proxy);
+	proxy = NULL;
+    }
 #ifdef _WINSOCKAPI_
     if (initialized)
 	WSACleanup();