It is looking like make clean & make distclean don't clear some                
of the headers :(                                                              
I had a config with TT off and then turned it on then I got a                  
undefined TASK_EXTERN_PID for tt/gdb.c so I did a make clean,                  
still no luck, make distclean alas did not clear the problem,                  
so I just generated a new symlink tree to compile in, but I was                
startled that distclean did not clear out the configuration.