Do not prohibit zero proc argument in GC_register_disclaim_proc

(fix of commit 1d3675499)

* fnlz_mlc.c [ENABLE_DISCLAIM] (GC_register_disclaim_proc): Do not
check that proc is non-zero.
* include/gc/gc_disclaim.h (GC_register_disclaim_proc): Remove
GC_ATTR_NONNULL(2) attribute.
* reclaim.c [ENABLE_DISCLAIM] (GC_disclaim_and_reclaim): Add assertion
that disclaim is non-zero.

1 files changed, 1 insertions, 0 deletions

diff --git a/reclaim.c b/reclaim.c
index a43a5182..e5e66d74 100644
--- a/reclaim.c
+++ b/reclaim.c
@@ -247,6 +247,7 @@ STATIC ptr_t GC_reclaim_uninit(struct hblk *hbp, hdr *hhdr, word sz,
     int (GC_CALLBACK *disclaim)(void *) =
                 GC_obj_kinds[hhdr -> hb_obj_kind].ok_disclaim_proc;
 
+    GC_ASSERT(disclaim != 0);
 #   ifndef THREADS
       GC_ASSERT(sz == hhdr -> hb_sz);
 #   endif