* libguile/weak-set.c (make_weak_set):
* libguile/weak-table.c (make_weak_table): If we have a threaded Guile,
* keep a weak set (table) of weak sets (tables). Use this and the
pthread_atfork mechanism to lock and unlock weak sets and weak tables
during a fork().
* libguile/weak-set.h (scm_weak_set_prehistory): New internal API.
* libguile/init.c: Add call to scm_weak_set_prehistory().
* libguile/weak-set.c:
* libguile/weak-set.h: New files, implementing weak sets, for use in the
symbol table and port set. Eventually we will be able to remove weak
pairs.
* libguile.h:
* libguile/Makefile.am: Add new files.
* libguile/evalext.c:
* libguile/gc.c:
* libguile/init.c:
* libguile/print.c:
* libguile/tags.h: Add support for the new types.
