[mod_extforward] reset cond_cache for scheme (fixes #1499)

bug #1499 was mostly fixed in 05858f6c
This patch additionally resets the cond_cache since scheme might change

x-ref:
  "HTTPS env var should be "on" when using mod_extforward and the X-Forwarded-Proto header is set."
  https://redmine.lighttpd.net/issues/1499

NEWS

@@ -66,6 +66,7 @@ NEWS
   * [mod_cgi] always set QUERY_STRING (fixes #1339)
   * [mod_auth] send charset="UTF-8" in WWW-Authenticate (fixes #1468)
   * [mod_magnet] rename var for clarity (fixes #1483)
+  * [mod_extforward] reset cond_cache for scheme (fixes #1499)
 
 - 1.4.39 - 2016-01-02
   * [core] fix memset_s call (fixes #2698)

src/mod_extforward.c

@@ -352,6 +352,7 @@ static void ipstr_to_sockaddr(server *srv, const char *host, sock_addr *sock) {
 
 static void clean_cond_cache(server *srv, connection *con) {
 	config_cond_cache_reset_item(srv, con, COMP_HTTP_REMOTE_IP);
+	config_cond_cache_reset_item(srv, con, COMP_HTTP_SCHEME);
 }
 
 URIHANDLER_FUNC(mod_extforward_uri_handler) {