Fetch ResourceId even for handle == 0

* This happens in two cases - the legal one for FBO 0 (the window's
  backbuffer) - and the compatibility one for VAO 0.

renderdoc/driver/gl/gl_resources.cpp

@@ -57,7 +57,7 @@ void DoSerialise(SerialiserType &ser, GLResource &el)
 
   ResourceId id;
 
-  if(ser.IsWriting() && rm && el.name)
+  if(ser.IsWriting() && rm)
     id = rm->GetID(el);
 
   DoSerialise(ser, id);