fork_child_proc() reinitialized mark_mutex and GC_allocate_ml in the
forked child with pthread_mutex_init()/pthread_rwlock_init(), aborting
the child when the call failed. A statically initialized lock of the
same type is equivalent to initializing with NULL attributes, so copy
one over the live lock with BCOPY instead; the GC_allocate_ml rwlock
branch already did exactly that.
This removes the init calls from the child (which are slower and can
fail) and with them the two ABORT paths, so a plain fork() in a
multi-threaded program no longer depends on pthread_*_init() succeeding
in the single-threaded child.
diviocity
f3fd9f493f