(a cherry-pick of
34c88d306 from 'racket_gc')
* ChangeLog (6.2alpha4): Fix typo ("primitives").
* Separate gc_conf_macros.h from gc.h.
* Added generic GC_THREADS client-defined macro to set the appropriate
GC_XXX_THREADS internal macro. (gc_config_macros.h.)
-* Add debugging versions of _ignore_off_page allocation primitves.
+* Add debugging versions of _ignore_off_page allocation primitives.
* Moved declarations of GC_make_closure and GC_debug_invoke_finalizer
from gc.h to gc_priv.h.
* Reset GC_fail_count even if only a small allocation succeeds.