bp/Request: initializer stateless

The initializer for this field has always been missing, but I thought
that was okay because it was not used before it was initialized by
DetermineSession(), but if ParseRequestUri() fails, a "400 Bad
Request" response was generated to early.

The assertion failure never occurred memory poisoning implicitly
initialized this field to `true`, but commit
36422d7 disabled memory poisoning.

debian/changelog

@@ -1,6 +1,6 @@
 cm4all-beng-proxy (19.1) unstable; urgency=low
 
-  * 
+  * bp: fix crash due to uninitialized variable
 
  --   
 

src/bp/Request.hxx

@@ -412,7 +412,7 @@ private:
 	 * disabled?  This is initialized by DetermineSession(), and
 	 * may be disabled later by HandleTranslatedRequest().
 	 */
-	bool stateless;
+	bool stateless = true;
 
 	bool send_session_cookie = false;