Invoke GC_oom_fn if GC_make_array_descriptor failed because of no memory

(a cherry-pick of commit 223ce4f from 'master')

* typd_mlc.c (GC_calloc_explicitly_typed): If descr_type is NO_MEM then
return the result of GC_get_oom_fn()(lb) instead of NULL.

typd_mlc.c

@@ -677,7 +677,8 @@ GC_API GC_ATTR_MALLOC void * GC_CALL GC_calloc_explicitly_typed(size_t n,
                                           &complex_descr, &leaf);
     lb *= n;
     switch(descr_type) {
-        case NO_MEM: return(0);
+        case NO_MEM:
+            return (*GC_get_oom_fn())(lb);
         case SIMPLE:
             return GC_malloc_explicitly_typed(lb, simple_descr);
         case LEAF: