TEST: Make AGC margin tests work in single threaded version.

Author: JanWielemaker

tests/core/test_agc_margin.pl

@@ -73,6 +73,7 @@
 %  run without the GC thread.  Everything is restored afterwards: the text
 %  margin is global state shared with the rest of the suite.
 
+:- if(current_prolog_flag(threads, true)).
 setup_agc(state(Thread, Margin)) :-
     current_prolog_flag(gc_thread, Thread),
     blob_type_property(text, gc_margin(Margin)),
@@ -83,6 +84,17 @@
     set_blob_type(text, gc_margin(Margin)),
     set_prolog_flag(gc_thread, Thread).
 
+:- else.
+
+setup_agc(state(Margin)) :-
+    blob_type_property(text, gc_margin(Margin)),
+    garbage_collect_atoms.
+
+cleanup_agc(state(Margin)) :-
+    set_blob_type(text, gc_margin(Margin)).
+
+:- endif.
+
 
 :- begin_tests(agc_margin_api).