keep track that we are exiting unbdefp handler, even if we exit with a throw.

git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@1250 b08c6af1-5177-4d33-ba66-4b1c6b8b522a

C/tracer.c

@@ -120,8 +120,6 @@ low_level_trace(yap_low_level_port port, PredEntry *pred, CELL *args)
   /*  extern int gc_calls; */
 
   vsc_count++;
-  if (vsc_count < 3590LL)
-    return;
 #ifdef COMMENTED
   //  if (vsc_count == 218280)
   //    vsc_xstop = 1;

pl/boot.yap

@@ -737,15 +737,18 @@ not(G) :-    \+ '$execute'(G).
 	'$execute0'(NG,M).
 '$do_undefp'(G,M) :-
 	\+ '$undefined'(unknown_predicate_handler(_,_,_), user),
-	'$system_catch'(unknown_predicate_handler(G,M,NG), user, _, fail), !,
-	( once('$execute'(user:NG)) -> '$exit_undefp' ; '$exit_undefp', fail).
+	( '$system_catch'(NG,user,Error,'$leave_undefp'(Error)) -> '$exit_undefp' ; '$exit_undefp', fail).
 '$do_undefp'(G,M) :-
 	recorded('$unknown','$unknown'(M:G,US),_), !,
-	( once('$execute'(user:US)) -> '$exit_undefp' ; '$exit_undefp', fail).
+	( '$system_catch'(US,user,Error,'$leave_undefp'(Error)) -> '$exit_undefp' ; '$exit_undefp', fail).
 '$do_undefp'(_,_) :-
 	'$exit_undefp',
 	fail.
 
+'$leave_undefp'(Ball) :-
+	'$exit_undefp',
+	throw(Ball).
+
 
 /* This is the break predicate,
 	it saves the importante data about current streams and